Primary Offering Prospectus - Form 424B2

Filed Pursuant to Rule 424(b)(2)
Registration No. 333-278993

The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been filed with and declared effective by the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell and are not soliciting offers to buy these securities in any state where such offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED OCTOBER 10, 2024

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus dated April 29, 2024)

Carlyle Secured Lending, Inc.

$    

 % Notes due

We operate as a closed-end, externally managed, non-diversified management investment company and have elected to be regulated as a business development company under the Investment Company Act of 1940, as amended. For U.S. federal income tax purposes, we have elected to be treated as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended. Our investment objective is to generate current income and, to a lesser extent, capital appreciation primarily through assembling a portfolio of secured debt investments in U.S. middle market companies. Our core investment strategy focuses on lending to U.S. middle market companies, which we define as companies with approximately $25 million to $100 million of earnings before interest, taxes, depreciation and amortization, supported by financial sponsors. This core strategy is opportunistically supplemented with differentiated and complementary lending and investing strategies, which take advantage of the broad capabilities of Carlyle's Global Credit platform while offering risk-diversifying portfolio benefits. We seek to achieve our investment objective primarily through direct origination of secured debt instruments, including first lien senior secured loans (which may include stand-alone first lien loans, first lien/last out loans and "unitranche" loans) and second lien senior secured loans (collectively, "Middle Market Senior Loans"), with a minority of our assets invested in higher yielding investments (which may include unsecured debt, subordinated debt and investments in equities). The Middle Market Senior Loans are generally made to private U.S. middle market companies that are, in many cases, controlled by private equity firms.

We are offering $  million in aggregate principal amount of  % notes due      (the "Notes"). The Notes will mature on    ,    . We will pay interest on the Notes on    and    of each year, beginning on    , 2025. We may redeem the Notes in whole or in part at any time or from time to time at the redemption price as set forth under "Description of the Notes-Optional Redemption" in this prospectus supplement. In addition, holders of the Notes can require us to repurchase the Notes at 100% of their principal amount upon the occurrence of a Change of Control Repurchase Event (as defined herein). The Notes will be issued in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof.

The Notes will be our direct unsecured obligations and rank equal in right of payment with all outstanding and future unsecured, unsubordinated indebtedness issued by us (including our 4.750% senior unsecured notes due December 31, 2024 (the "2024 4.750% Notes"), our 4.500% senior unsecured notes due December 31, 2024 (the "2024 4.500% Notes") and our 8.20% senior unsecured notes due December 1, 2028 (the "2028 Notes")). Because the Notes will not be secured by any of our assets, they will be effectively subordinated to any existing and future secured indebtedness of Carlyle Secured Lending, Inc. (including borrowings under our senior secured revolving credit facility), or any indebtedness that is initially unsecured as to which we subsequently grant a security interest, to the extent of the value of the assets securing such indebtedness. The Notes will be structurally subordinated to all existing and future indebtedness and other obligations of any of our subsidiaries (including notes issued by our wholly-owned consolidated subsidiary, Carlyle Direct Lending CLO 2015-1R LLC (the "2015-1R Notes")) since the Notes will be obligations exclusively of Carlyle Secured Lending, Inc. and not of any of our subsidiaries. The Notes will be senior in right of payment to our common stock, our cumulative convertible preferred stock (the "Preferred Stock") and any additional series of our preferred stock we may issue in the future. None of our subsidiaries is a guarantor of the Notes and the Notes will not be required to be guaranteed by any subsidiary we may acquire or create in the future.

Investing in the Notes involves a high degree of risk, including the risk of leverage. Before buying any Notes, you should read the material risks described in the "Supplementary Risk Factors" section beginning on page S-8 of this prospectus supplement and in the "Risk Factors" section beginning on page 14 of the accompanying prospectus and under similar headings in the other documents that we file from time to time with the Securities and Exchange Commission (the "SEC"), that are incorporated by reference into this prospectus supplement and the accompanying prospectus.

The Notes are not deposits or other obligations of a bank and are not insured by the Federal Deposit Insurance Corporation or any other government agency.

This prospectus supplement, the accompanying prospectus, any free writing prospectus, and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus contain important information you should know before investing in the Notes, including information about risks. Please read these documents before you invest and retain them for future reference. Additional information about us, including our annual, quarterly and current reports, has been filed with the SEC and can be accessed free of charge at its website at www.sec.gov. This information is also available free of charge by calling us at (212) 813-4900 or on the Investor Resources section of our corporate website located at http://carlylesecuredlending.com/, which, except for the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, is not part of this prospectus supplement nor the accompanying prospectus. You may also call us collect at this number to request other information or to make an investor inquiry. See "Where You Can Find More Information" in this prospectus supplement.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Delivery of the Notes in book-entry form only through The Depository Trust Company for the accounts of its participants, including Euroclear Bank S.A./N.V., as operator of the Euroclear System, and Clearstream Banking S.A., will be made on or about     , 2024.

Joint Book-Running Managers

The date of this prospectus supplement is     , 2024.

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

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ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement, the accompanying prospectus, any free writing prospectus that we may authorize for use in connection with this offering and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus set forth the information that you should know before investing in the Notes. You should read these documents, which contain important information, particularly the information described under the "Supplementary Risk Factors" included in this prospectus supplement, "Risk Factors" included in the accompanying prospectus, our most recently filed Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q, and under similar headings in the other documents incorporated by reference into this prospectus supplement and the accompanying prospectus, before deciding whether to invest in the Notes.

This prospectus supplement, which describes the specific terms of this offering, also adds to and updates information contained in the accompanying prospectus. The accompanying prospectus gives more general information, some of which may not apply to this offering. If the description of this offering varies between this prospectus supplement and the accompanying prospectus, you should rely on the information contained in this prospectus supplement. However, if any statement in one of these documents is inconsistent with a statement in another document having a later date, the statement in the document having the later date modifies or supersedes the earlier statement.

We are responsible for the information contained in this prospectus supplement, the accompanying prospectus, any free writing prospectus that we may authorize for use in connection with this offering and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. Neither we nor the underwriters have authorized any other person to provide you with different or inconsistent information, and we take no responsibility for any other information others may give you. The information appearing in this prospectus supplement, the accompanying prospectus, any free writing prospectus that we may authorize for use in connection with this offering and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus is accurate only as of the respective dates of such information regardless of the time of delivery or any sale of the Notes. Our business, financial condition, results of operations and prospects may have changed since those dates.

We are not, and the underwriters are not, making an offer to sell the Notes in any jurisdiction where such an offer or sale is not permitted.

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SUPPLEMENTARY RISK FACTORS

Investing in the Notes involves a number of significant risks. You should carefully consider the risks described below and all other information contained in this prospectus supplement, the accompanying prospectus, any free writing prospectus authorized for use by us and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus before making a decision to purchase the Notes. The risks and uncertainties described below are not the only ones facing us. Additional risks and uncertainties not presently known to us, or not presently deemed material by us, may also impair our operations and performance. If any of the following risks actually occur, our business, financial condition or results of operations could be materially adversely affected. If that happens, the trading price of the Notes could decline and you may lose all or part of your investment.

Risks Related to the Notes

The Notes will be unsecured and therefore will be effectively subordinated to any existing and future secured indebtedness and will rank pari passu with, or equal to, all outstanding and future unsecured indebtedness issued by us, including the 2024 4.750% Notes, the 2024 4.500% Notes and the 2028 Notes, and our general liabilities.

The Notes will not be secured by any of our assets or any of the assets of our subsidiaries. As a result, the Notes will be effectively subordinated to any secured indebtedness we have outstanding as of the date of this prospectus supplement, including $236.2 million outstanding under our Credit Facility as of June 30, 2024, or that we may incur in the future (or any indebtedness that is initially unsecured to which we subsequently grant security) to the extent of the value of the assets securing such indebtedness. In any liquidation, dissolution, bankruptcy or other similar proceeding, the holders of any of our existing or future secured indebtedness and the secured indebtedness of our subsidiaries may assert rights against the assets pledged to secure that indebtedness in order to receive full payment of their indebtedness before the assets may be used to pay other creditors, including the holders of the Notes. In addition, the Notes will rank pari passu with, or equal to, all outstanding and future unsecured indebtedness issued by us, of which we had $275 million aggregate principal amount outstanding as of June 30, 2024, including the 2024 4.750% Notes, the 2024 4.500% Notes and the 2028 Notes, and our general liabilities.

The Notes will be structurally subordinated to the indebtedness and other liabilities of our subsidiaries.

The Notes will be obligations exclusively of CGBD and not of any of our subsidiaries. None of our subsidiaries will be a guarantor of the Notes and the Notes will not be required to be guaranteed by any subsidiaries we may acquire or create in the future. Any assets of our subsidiaries will not be directly available to satisfy the claims of our creditors, including holders of the Notes. Except to the extent we are a creditor with recognized claims against our subsidiaries, all claims of creditors of our subsidiaries will have priority over our equity interests in such subsidiaries (and therefore the claims of our creditors, including holders of the Notes) with respect to the assets of such subsidiaries. Even if we are recognized as a creditor of one or more of our subsidiaries, our claims would still be effectively subordinated to any security interests in the assets of any such subsidiary and to any indebtedness or other liabilities of any such subsidiary senior to our claims. Consequently, the Notes will be structurally subordinated to all indebtedness and other liabilities of any of our subsidiaries and any subsidiaries that we may in the future acquire or establish, including SPV and 2015-1 Issuer. As of June 30, 2024, there was approximately $400 million of debt outstanding under the 2015-1R Notes. Borrowings under the 2015-1R Notes are the obligation of 2015-1 Issuer, a wholly-owned subsidiary of ours, and are structurally senior to the Notes. In addition, our subsidiaries may incur substantial additional indebtedness in the future, all of which would be structurally senior to the Notes.

The indenture under which the Notes will be issued will contain limited protection for holders of the Notes.

The indenture under which the Notes will be issued offers limited protection to holders of the Notes. The terms of the indenture and the Notes do not restrict our or any of our subsidiaries' ability to engage in, or otherwise be

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a party to, a variety of corporate transactions, circumstances or events that could have a material adverse impact on your investment in the Notes. In particular, the terms of the indenture and the Notes will not place any restrictions on our or our subsidiaries' ability to:

Furthermore, the terms of the indenture and the Notes do not protect holders of the Notes in the event that we experience changes (including significant adverse changes) in our financial condition, results of operations or credit ratings, if any, as they do not require that we or our subsidiaries adhere to any financial tests or ratios or specified levels of net worth, revenues, income, cash flow, or liquidity.

Our ability to recapitalize, incur additional debt (including additional debt that matures prior to the maturity of the Notes) and take a number of other actions that are not limited by the terms of the Notes may have important consequences for you as a holder of the Notes, including making it more difficult for us to satisfy our obligations with respect to the Notes or negatively affecting the trading value of the Notes.

Certain of our current debt instruments include more protections for their holders than the indenture and the Notes. In addition, other debt we issue or incur in the future could contain more protections for its holders than the indenture and the Notes, including additional covenants and events of default. The issuance or incurrence of any such debt with incremental protections could affect the market for, trading levels, and prices of the Notes.

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We cannot assure that an active trading market will be maintained for the Notes.

The Notes are a new issue of debt securities and there currently is no trading market for the Notes. We do not intend to apply for listing of the Notes on any securities exchange or for quotation of the Notes on any automated dealer quotation system. If no active trading market develops, you may not be able to resell your Notes at their fair market value or at all. If the Notes are traded after their initial issuance, they may trade at a discount from their initial offering price depending on prevailing interest rates, the market for similar securities, our credit ratings, general economic conditions, our financial condition, performance and prospects and other factors. Certain of the underwriters have advised us that they currently intend to make a market in the Notes but they are not obligated to do so. The underwriters may discontinue any market-making in the Notes at any time at their sole discretion. In addition, any market-making activity will be subject to limits imposed by law. Accordingly, we cannot assure you that a liquid trading market will be maintained for the Notes, that you will be able to sell your Notes at a particular time or that the price you receive when you sell will be favorable. To the extent an active trading market is not maintained, the liquidity and trading price for the Notes may be harmed. Accordingly, you may be required to bear the financial risk of an investment in the Notes for an indefinite period of time.

The amount of our debt outstanding will increase as a result of this offering, and if we default on our obligations to pay our other indebtedness, we may not be able to make payments on the Notes.

Any default under the agreements governing our indebtedness, including a default under the Credit Facility, the terms of the 2024 4.750% Notes, the 2024 4.500% Notes and the 2028 Notes or other indebtedness to which we may be a party, that is not waived by the required lenders or holders, and the remedies sought by the lenders or holders of such indebtedness, could make us unable to pay principal, premium, if any, and interest on the Notes and substantially decrease the market value of the Notes. If we are unable to generate sufficient cash flow and are otherwise unable to obtain funds necessary to meet required payments of principal, premium, if any, and interest on our indebtedness, or if we otherwise fail to comply with the various covenants, including financial and operating covenants, as applicable, in the instruments governing our indebtedness, we could be in default under the terms of the agreements governing such indebtedness. In the event of such default, the holders of such indebtedness could elect to declare all the funds borrowed thereunder to be due and payable, together with accrued and unpaid interest, the lenders under the Credit Facility or other debt we may incur in the future could elect to terminate their commitments, cease making further loans and institute foreclosure proceedings against our assets, and we could be forced into bankruptcy or liquidation.

Our ability to generate sufficient cash flow in the future is, to some extent, subject to general economic, financial, competitive, legislative and regulatory factors as well as other factors that are beyond our control. We cannot assure you that our business will generate cash flow from operations, or that future borrowings will be available to us under the Credit Facility or otherwise, in an amount sufficient to enable us to meet our payment obligations under the Notes, the 2024 4.750% Notes, the 2024 4.500% Notes, the 2028 Notes and the Credit Facility, and to fund other liquidity needs.

If our operating performance declines and we are not able to generate sufficient cash flow to service our debt obligations, we may in the future need to refinance or restructure our debt, including the Notes, sell assets, reduce or delay capital investments, seek to raise additional capital or seek to obtain waivers from the required lenders under the Credit Facility or the holders of the 2024 4.750% Notes, the 2024 4.500% Notes and the 2028 Notes or other debt that we may incur in the future to avoid being in default. If we are unable to implement one or more of these alternatives, we may not be able to meet our payment obligations under the Notes or our other debt. If we breach our covenants under the Credit Facility, the 2024 4.750% Notes, the 2024 4.500% Notes, the 2028 Notes or other debt and seek a waiver, we may not be able to obtain a waiver from the required lenders or holders. If this occurs, we would be in default under the Credit Facility, the 2024 4.750% Notes, the 2024 4.500% Notes, the 2028 Notes or other debt, the lenders or holders could exercise their rights as described above, and we could be forced into bankruptcy or liquidation. If we are unable to repay debt, lenders having secured obligations,

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including the lenders under the Credit Facility, could proceed against the collateral securing the debt. Because the Credit Facility, the 2024 4.750% Notes and the 2024 4.500% Notes have, and any future credit facilities or other indebtedness will likely have, customary cross-default provisions, if the indebtedness under the Notes, the 2024 4.750% Notes, the 2024 4.500% Notes or the Credit Facility or under any future credit facility or other indebtedness is accelerated, we may be unable to repay or finance the amounts due.

The optional redemption provision may materially adversely affect your return on the Notes.

The Notes are redeemable in whole or in part upon certain conditions at any time or from time to time at our option. We may choose to redeem the Notes at times when prevailing interest rates are lower than the interest rate paid on the Notes. In this circumstance, you may not be able to reinvest the redemption proceeds in a comparable security at an effective interest rate as high as that of the Notes being redeemed.

We may not be able to repurchase the Notes upon a Change of Control Repurchase Event.

We may not be able to repurchase the Notes upon a Change of Control Repurchase Event because we may not have sufficient funds. Upon the occurrence of a Change of Control Repurchase Event, as defined in the indenture that governs the Notes, as supplemented, subject to certain conditions, we will be required to offer to repurchase all outstanding Notes at 100% of their principal amount, plus accrued and unpaid interest. The source of funds for that purchase of Notes will be our available cash or cash generated from our operations or other potential sources, including borrowings, investment repayments, sales of assets or sales of equity. We cannot assure you that sufficient funds from such sources will be available at the time of any Change of Control Repurchase Event to make required repurchases of Notes tendered. The terms of the Credit Facility provide that certain change of control events will constitute an event of default thereunder entitling the lenders to accelerate any indebtedness outstanding under the Credit Facility at that time and to terminate the Credit Facility.

Any failure to comply with these provisions would constitute an event of default under each of the other agreements governing our indebtedness, including the indenture. Our future debt instruments also may contain similar restrictions and provisions. If the holders of the Notes exercise their right to require us to repurchase all the Notes upon a Change of Control Repurchase Event, the financial effect of this repurchase could cause a default under our future debt instruments, even if the Change of Control Repurchase Event itself would not cause a default. It is possible that we will not have sufficient funds at the time of the Change of Control Repurchase Event to make the required repurchase of the Notes or our other debt. See "Description of Notes-Offer to Repurchase Upon a Change of Control Repurchase Event."

Our management will have broad discretion in the use of a substantial portion of the net proceeds from this offering and may allocate the net proceeds from this offering in ways that you and other securityholders may not approve.

Our management will have broad discretion in the use of a substantial portion of the net proceeds, including for any of the purposes described in the section entitled "Use of Proceeds," and you will not have the opportunity as part of your investment decision to assess whether the net proceeds are being used in ways with which you may not agree or may not otherwise be considered appropriate. Because of the number and variability of factors that will determine our use of the net proceeds from this offering, their ultimate use may vary substantially from their currently intended use. The failure of our management to use these funds effectively could harm our business. Pending their use, we may invest a portion of net proceeds from this offering in short-term, investment-grade, interest-bearing securities. These investments may not yield a favorable return to us or our stockholders.

A downgrade, suspension or withdrawal of any credit rating assigned by a rating agency to us or the Notes or change in the debt markets could cause the liquidity or market value of the Notes to decline significantly.

Any credit rating is an assessment by rating agencies of our ability to pay our debts when due. Consequently, real or anticipated changes in any credit ratings will generally affect the market value of the Notes. These credit

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ratings may not reflect the potential impact of risks relating to the structure or marketing of the Notes. Credit ratings are not a recommendation to buy, sell or hold any security, and may be revised or withdrawn at any time by the issuing organization in its sole discretion. Neither we nor any underwriter undertakes any obligation to obtain or maintain any credit ratings or to advise holders of Notes of any changes in any credit ratings. There can be no assurance that any credit ratings will remain for any given period of time or that such credit ratings will not be lowered or withdrawn entirely by the rating agencies if in their judgment future circumstances relating to the basis of the credit ratings, such as adverse changes in our Company, so warrant. The conditions of the financial markets and prevailing interest rates have fluctuated in the past and are likely to fluctuate in the future, which could have an adverse effect on the market prices of the Notes.

Risks relating to the Mergers

We may be unable to realize the benefits anticipated by the Mergers, including estimated cost savings, or it may take longer than anticipated to achieve such benefits.

The realization of certain benefits anticipated as a result of the Mergers will depend in part on the integration of CSL III's investment portfolio with our investment portfolio and the integration of CSL III's business with our business. There can be no assurance that CSL III's investment portfolio or business can be operated profitably going forward or integrated successfully into our operations in a timely fashion or at all. The dedication of management resources to such integration may detract attention from the day-to-day business of the combined company and there can be no assurance that there will not be substantial costs associated with the transition process or there will not be other material adverse effects as a result of these integration efforts. Such effects, including incurring unexpected costs or delays in connection with such integration and failure of CSL III's investment portfolio to perform as expected, could have a material adverse effect on the financial results of the combined company.

We also expect to achieve certain synergies and cost savings from the Mergers when the two companies have fully integrated their portfolios. It is possible that the estimates of these synergies and potential cost savings could ultimately be incorrect. The cost savings estimates also assume we will be able to combine our operations and CSL III's operations in a manner that permits those cost savings to be fully realized. If the estimates turn out to be incorrect or if we are not able to successfully combine the CSL III investment portfolio or business with our operations, the anticipated synergies and cost savings may not be fully realized or realized at all or may take longer to realize than expected.

If the Mergers do not close, we will not benefit from the expenses incurred in pursuit of the Mergers.

If the Mergers do not close, we will have incurred substantial expenses for which no ultimate benefit will have been received. We have incurred out-of-pocket expenses in connection with the Mergers for investment banking, legal and accounting fees and financial printing and other related charges, much of which will be incurred even if the Mergers are not completed.

The termination of the Merger Agreement could negatively impact us.

If the Merger Agreement is terminated, there may be various consequences, including:

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The Merger Agreement limits our ability to pursue alternatives to the Mergers.

The Merger Agreement contains provisions that limit our ability to discuss, facilitate or commit to competing third party proposals to acquire all or a significant part of us (a "Takeover Proposal"), which are typical for transactions of this type. In certain circumstances relating to a Takeover Proposal, a termination fee of $26 million would be payable by the Company to CSL III, as is customary for transactions of this type. The termination fee might discourage a potential competing acquirer that might have an interest in acquiring all or a significant part of us from considering or proposing that acquisition even if it were prepared to pay consideration with a higher per share market price than that proposed in the Mergers or might result in a potential competing acquirer proposing to pay a lower per share price to acquire us than it might otherwise have proposed to pay.

The Mergers are subject to closing conditions, including stockholder approvals, that, if not satisfied or (to the extent legally allowed) waived, will result in the Mergers not being completed, which may result in material adverse consequences to our business and operations.

The completion of the Mergers remains subject to the satisfaction of certain customary closing conditions, including among others (1) requisite approval of our stockholders, (2) authorization of the shares of our common stock to be issued as consideration in the Mergers for listing on Nasdaq, (3) effectiveness of the registration statement for our common stock to be issued as consideration in the Mergers, (4) the absence of certain legal impediments to the consummation of the Mergers, (5) required regulatory approvals (including expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended), (6) determinations of Closing CGBD Net Asset Value (as defined in the Merger Agreement) in accordance with the terms of the Merger Agreement, (7) the Preferred Stock Exchange Documents (as defined in the Merger Agreement) by and between us and the holder of Preferred Stock remain in full force and effect as of the effective time of the Preferred Stock Exchange (as defined in the Merger Agreement) in accordance with the Merger Agreement and (8) subject to certain exceptions, the accuracy of the representations and warranties and compliance with the covenants of each party to the Merger Agreement. Therefore, the Mergers may not be completed or may not be completed as timely as expected.

The closing condition that our stockholders approve the issuance of shares of our common stock pursuant to the Merger Agreement may not be waived and must be satisfied for the Mergers to be completed. If our stockholders do not approve the issuance of shares of our common stock pursuant to the Merger Agreement and the Mergers are not completed, the resulting failure of the Mergers could have a material adverse impact on our business and operations. In addition to the required approvals of our stockholders, the Mergers are subject to a number of other conditions beyond our control that may prevent, delay or otherwise materially adversely affect completion of the Mergers. We cannot predict whether and when these other conditions will be satisfied.

We may, to the extent legally allowed, waive one or more conditions to the Mergers without resoliciting stockholder approval.

Certain conditions to our obligations to complete the Mergers may be waived, in whole or in part, to the extent legally allowed, either unilaterally or by agreement with CSL III. In the event that any such waiver does not require resolicitation of stockholders, we will have the discretion to complete the Mergers without seeking further stockholder approval. The conditions requiring the approval of our stockholders, however, cannot be waived.

We will be subject to operational uncertainties and contractual restrictions while the Mergers are pending.

Uncertainty about the effect of the Mergers may have an adverse effect on us and, consequently, on the combined company following completion of the Mergers.

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These uncertainties may cause those that deal with us to seek to change their existing business relationships with us. In addition, the Merger Agreement restricts us from taking actions that we might otherwise consider to be in our best interests. These restrictions may prevent us from pursuing certain business opportunities that may arise prior to the completion of the Mergers.

Litigation against us, CSL III, or the members of our Board of Directors and CSL III's board of trustees, could prevent or delay the completion of the Mergers or result in the payment of damages following completion of the Mergers.

It is possible that lawsuits may be filed by our stockholders or CSL III's shareholders challenging the Mergers. The outcome of such lawsuits cannot be assured, including the amount of costs associated with defending these claims or any other liabilities that may be incurred in connection with the litigation of these claims. If plaintiffs are successful in obtaining an injunction prohibiting the parties from completing the Mergers, such injunction may delay the consummation of the Mergers in the expected timeframe, or may prevent the Mergers from being consummated at all. Whether or not any plaintiff's claim is successful, this type of litigation can result in significant costs and divert management's attention and resources from the closing of the Mergers and ongoing business activities, which could adversely affect the operations of the Company.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

Information contained or incorporated by reference into this prospectus supplement, the accompanying prospectus, and in any free writing prospectus relating to this offering other than historical facts, may constitute "forward-looking statements." These statements may relate to, among other things, future events or our future performance or financial condition, our business prospects and the prospects of our portfolio companies, actual and potential conflicts of interest with our Investment Adviser and its affiliates, the use of borrowed money to finance our investments, the adequacy of our financing sources and working capital, and our ability to co-invest, among other factors. In some cases, you can identify forward-looking statements by terminology such as "estimate," "may," "might," "believe," "will," "provided," "anticipate," "future," "could," "growth," "plan," "project," "intend," "expect," "should," "would," "if," "seek," "possible," "potential," "likely" or the negative or variations of such terms or comparable terminology. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statements. Such factors include:

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We caution readers not to place undue reliance on any such forward-looking statements, which speak only as of the date made. Actual results could differ materially from those anticipated in our forward-looking statements and future results could differ materially from our historical performance. We have based forward-looking statements on information available to us on the date of this prospectus supplement. Except as required by law, we undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, after the date of this prospectus supplement. Although we undertake no obligation to revise or update any forward-looking statements, whether as a result of new information, future events, or otherwise, you are advised to consult any additional disclosures that we may make directly to you or through reports or other documents we have filed, or in the future may file, with the SEC, including subsequent annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K. The forward-looking statements contained in or incorporated by reference into this prospectus supplement and the accompanying prospectus are excluded from the safe harbor protection provided by the Private Securities Litigation Reform Act of 1995 and Section 27A of the Securities Act of 1933, as amended (the "Securities Act").

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USE OF PROCEEDS

We estimate that net proceeds from the sale of $   aggregate principal amount of the Notes in this offering will be approximately $   after deducting the underwriting discount of $   payable by us and estimated offering expenses of approximately $   payable by us.

We intend to use the net proceeds from this offering to repay our outstanding debt including the Credit Facility, 2024 4.750% Notes and the 2024 4.500% Notes, to fund new investment opportunities, and for other general corporate purposes. The 2024 4.750% Notes and 2024 4.500% Notes are in an aggregate principal amount of approximately $190 million, each of which are scheduled to mature on December 31, 2024. The Credit Facility is scheduled to mature on August 31, 2028 and amounts drawn under the Credit Facility bear an interest rate of SOFR + 1.875% as of June 30, 2024.

Affiliates of certain of the underwriters are lenders under the Credit Facility. Accordingly, affiliates of certain of the underwriters may receive more than 5% of the proceeds of this offering to the extent such proceeds are used to repay or repurchase outstanding indebtedness under the Credit Facility.

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CAPITALIZATION

The following table sets forth our capitalization as of June 30, 2024:

You should read the data set forth in the table below in conjunction with the section titled "Use of Proceeds" and "Underwriting" appearing elsewhere in this prospectus supplement, as well as our unaudited financial statements and the accompanying notes and the section entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations," each included in our Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2024 and incorporated by reference into the this prospectus supplement and accompanying base prospectus.

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DESCRIPTION OF THE NOTES

The following is a description of particular terms of the Notes.

We will issue the Notes under the base indenture between us and U.S. Bank Trust Company, National Association, (as successor trustee to The Bank of New York Mellon Trust Company, N.A.), dated as of November 20, 2023, as supplemented by the First Supplemental Indenture between us and the trustee, dated as of November 20, 2023, and the separate second supplemental indenture between us and the trustee, to be dated as of the settlement date for the Notes. As used in this section, all references to the indenture mean the base indenture as supplemented by the second supplemental indenture. The terms of the Notes include those expressly set forth in the indenture and those made part of the indenture by reference to the Trust Indenture Act of 1939, as amended.

The following description is a summary of the material provisions of the Notes and the indenture and does not purport to be complete. This summary is subject to and is qualified by reference to all the provisions of the Notes and the indenture, including the definitions of certain terms used in the indenture. We urge you to read these documents because they, and not this description, define your rights as a holder of the Notes. The SEC maintains a website at www.sec.gov that contains information we file with the SEC, including the indenture.

For purposes of this description, references to "we," "our" and "us" refer only to Carlyle Secured Lending, Inc. and not to any of its current or future subsidiaries and references to "subsidiaries" refer to our consolidated subsidiaries and exclude any investments held by Carlyle Secured Lending, Inc. in the ordinary course of business which are not, under GAAP, consolidated on the financial statements of Carlyle Secured Lending, Inc. and its subsidiaries. Such references also include entities that engage in investment activities in securities or other assets that are primarily controlled by the Company. The Company complies with the provisions of the 1940 Act governing investment policies, capital structure, and leverage on an aggregate basis with its subsidiaries, and it treats subsidiary debt as its own. The principal investment strategies of the subsidiaries are substantially similar to those of the Company. The Company and its subsidiaries comply with provisions of the 1940 Act relating to affiliated transactions and custody.

General

The Notes:

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The indenture does not limit the amount of debt that may be issued by us or our subsidiaries under the indenture or otherwise. The indenture does not contain any financial covenants and does not restrict us from paying dividends or distributions or issuing or repurchasing our other securities. Other than restrictions described under "-Offer to Repurchase Upon a Change of Control Repurchase Event" and "-Covenants-Merger, Consolidation or Sale of Assets" in this prospectus supplement, the indenture does not contain any covenants or other provisions designed to afford holders of the Notes protection in the event of a highly leveraged transaction involving us or in the event of a decline in our credit rating as the result of a takeover, recapitalization, highly leveraged transaction or similar restructuring involving us that could adversely affect such holders.

We may, without the consent of the holders, issue additional Notes under the indenture with the same terms (except for the issue date, public offering price, and, if applicable, the initial interest payment date) as the Notes offered hereby in an unlimited aggregate principal amount; provided that, if such additional Notes are not fungible with the Notes offered hereby (or any other tranche of additional Notes) for U.S. federal income tax purposes, then such additional Notes will have different CUSIP numbers from the Notes offered hereby (and any such other tranche of additional Notes).

We do not intend to list the Notes on any securities exchange or any automated dealer quotation system.

Payments on the Notes; Paying Agent and Registrar; Transfer and Exchange

We will pay the principal of, and interest on, the Notes in global form registered in the name of or held by DTC or its nominee in immediately available funds to DTC or its nominee, as the case may be, as the registered holder of such Global Note (as defined below).

Payment of principal (and premium, if any) and any such interest on the Notes will be made at the corporate trust office of the trustee in such coin or currency of the United States as at the time of payment is legal tender for payment of public and private debts; provided, however, that at our option payment of interest may be made by check mailed to the address of the person entitled thereto as such address will appear in the security register.

A holder of Notes may transfer or exchange Notes at the office of the security registrar in accordance with the indenture. The security registrar and the trustee may require a holder, among other things, to furnish appropriate endorsements and transfer documents. No service charge will be imposed by us, the trustee or the security registrar for any registration of transfer or exchange of Notes, but we may require a holder to pay a sum sufficient to cover any transfer tax or other similar governmental charge required by law or permitted by the indenture.

The registered holder of a Note will be treated as its owner for all purposes.

Interest

The Notes will bear cash interest at a rate of  % per year until maturity. Interest on the Notes will accrue from     , 2024. Interest on the Notes will be payable semi-annually in arrears on     and      of each year, beginning on     , 2025.

Interest on the Notes will be paid to the person in whose name a Note is registered at 5:00 p.m. New York City time, or the close of business, on      or     , as the case may be, immediately preceding the relevant interest payment date. Interest on the Notes will be computed on the basis of a 360-day year composed of twelve 30-day months.

If any interest payment date, redemption date, the maturity date or any earlier required repurchase date upon a Change of Control Repurchase Event (defined below) of a Note falls on a day that is not a business day, the required payment will be made on the next succeeding business day and no interest on such payment will accrue

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in respect of the delay. The term "business day" means, with respect to any Note, any day other than a Saturday, a Sunday or a day on which banking institutions in New York are authorized or obligated by law or executive order to close.

Ranking

The Notes will be our direct general unsecured obligations and will rank:

As of June 30, 2024, our total consolidated indebtedness, at par, was approximately $911.2 million, $636.2 million of which was secured (of which $400 million was indebtedness of our subsidiaries) and $275 million of which was unsecured (none of which was indebtedness of our subsidiaries). See "Capitalization."

In the event of our bankruptcy, liquidation, reorganization or other winding up, our assets that secure secured debt will be available to pay obligations on the Notes only after all indebtedness under such secured debt has been repaid in full from such assets. We advise you that there may not be sufficient assets remaining to pay amounts due on any or all the Notes then outstanding.

Optional Redemption

Prior to the Par Call Date, we may redeem the Notes at our option, in whole or in part, at any time and from time to time, at a redemption price (expressed as a percentage of principal amount and rounded to three decimal places) equal to the greater of:

plus, in either case accrued and unpaid interest thereon to the redemption date of the Notes.

Notwithstanding the foregoing, at any time on or after the Par Call Date, we may redeem some or all of the Notes at any time, or from time to time, at a redemption price equal to 100% of the principal amount of the Notes to be redeemed plus, in each case, accrued and unpaid interest, if any, to, but excluding, the redemption date of the Notes.

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If we choose to redeem any Notes, we will deliver a notice of redemption to holders of the Notes to be redeemed not less than 10 nor more than 60 days before the redemption date. If we are redeeming less than all of the Notes, the particular Notes to be redeemed will be selected in accordance with the applicable procedures of the trustee and, so long as the Notes are registered to DTC or its nominee, the DTC; provided, however, that no such partial redemption will reduce the portion of the principal amount of a Note not redeemed to less than $2,000. Unless we default in payment of the redemption price, on and after the redemption date, interest will cease to accrue on the Notes or portions of the Notes called for redemption.

For purposes of calculating the redemption price in connection with the redemption of the Notes, on any redemption date, the following terms have the meanings set forth below:

"Par Call Date" means     , 20  ( month(s) prior to the maturity date of the Notes).

"Treasury Rate" means, with respect to any redemption date of the Notes, the yield determined by us in accordance with the following two paragraphs.

The Treasury Rate shall be determined by us after 4:15 p.m., New York City time (or after such time as yields on U.S. government securities are posted daily by the Board of Governors of the Federal Reserve System), on the third business day preceding the redemption date based upon the yield or yields for the most recent day that appear after such time on such day in the most recent statistical release published by the Board of Governors of the Federal Reserve System designated as "Selected Interest Rates (Daily)-H.15" (or any successor designation or publication) ("H.15") under the caption "U.S. government securities-Treasury constant maturities-Nominal" (or any successor caption or heading) ("H.15 TCM"). In determining the Treasury Rate, we shall select, as applicable: (1) the yield for the Treasury constant maturity on H.15 exactly equal to the period from the redemption date to the maturity date of the Notes (the "Remaining Life"); or (2) if there is no such Treasury constant maturity on H.15 exactly equal to the Remaining Life, the two yields-one yield corresponding to the Treasury constant maturity on H.15 immediately shorter than and one yield corresponding to the Treasury constant maturity on H.15 immediately longer than the Remaining Life-and shall interpolate to the Par Call Date on a straight-line basis (using the actual number of days) using such yields and rounding the result to three decimal places; or (3) if there is no such Treasury constant maturity on H.15 shorter than or longer than the Remaining Life, the yield for the single Treasury constant maturity on H.15 closest to the Remaining Life. For purposes of this paragraph, the applicable Treasury constant maturity or maturities on H.15 shall be deemed to have a maturity date equal to the relevant number of months or years, as applicable, of such Treasury constant maturity from the redemption date.

If on the third business day preceding the redemption date H.15 TCM is no longer published, we shall calculate the Treasury Rate based on the rate per annum equal to the semi-annual equivalent yield to maturity at 11:00 a.m., New York City time, on the second business day preceding such redemption date of the United States Treasury security maturing on, or with a maturity that is closest to, the Par Call Date, as applicable. If there is no United States Treasury security maturing on the Par Call Date but there are two or more United States Treasury securities with a maturity date equally distant from the Par Call Date, one with a maturity date preceding the Par Call Date and one with a maturity date following the Par Call Date, we shall select the United States Treasury security with a maturity date preceding the Par Call Date. If there are two or more United States Treasury securities maturing on the Par Call Date or two or more United States Treasury securities meeting the criteria of the preceding sentence, we shall select from among these two or more United States Treasury securities the United States Treasury security that is trading closest to par based upon the average of the bid and asked prices for such United States Treasury securities at 11:00 a.m., New York City time. In determining the Treasury Rate in accordance with the terms of this paragraph, the semi-annual yield to maturity of the applicable United States Treasury security shall be based upon the average of the bid and asked prices (expressed as a percentage of principal amount) at 11:00 a.m., New York City time, of such United States Treasury security, and rounded to three decimal places. Our actions and determinations in determining the redemption price of any of the Notes shall be conclusive and binding for all purposes, absent manifest error.

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Offer to Repurchase Upon a Change of Control Repurchase Event

If a Change of Control Repurchase Event occurs, unless we have exercised our right to redeem the Notes in full, we will make an offer to each holder of the Notes to repurchase all or any part (in minimum denominations of $2,000 and integral multiples of $1,000 principal amount in excess thereof) of that holder's Notes at a repurchase price in cash equal to 100% of the aggregate principal amount of Notes repurchased plus any accrued and unpaid interest on the Notes repurchased to, but not including, the date of purchase. Within 30 days following any Change of Control Repurchase Event or, at our option, prior to any Change of Control, but after the public announcement of the Change of Control, we will mail a notice to each holder describing the transaction or transactions that constitute or may constitute the Change of Control Repurchase Event and offering to repurchase Notes on the payment date specified in the notice, which date will be no earlier than 30 days and no later than 60 days from the date such notice is mailed. The notice will, if mailed prior to the date of consummation of the Change of Control, state that the offer to purchase is conditioned on the Change of Control Repurchase Event occurring on or prior to the payment date specified in the notice. We will comply with the requirements of Rule 14e-1 promulgated under the Exchange Act and any other securities laws and regulations thereunder to the extent those laws and regulations are applicable in connection with the repurchase of the Notes as a result of a Change of Control Repurchase Event. To the extent that the provisions of any securities laws or regulations conflict with the Change of Control Repurchase Event provisions of the Notes, we will comply with the applicable securities laws and regulations and will not be deemed to have breached our obligations under the Change of Control Repurchase Event provisions of the Notes by virtue of such conflict.

On the Change of Control Repurchase Event payment date, subject to extension if necessary to comply with the provisions of the 1940 Act and the rules and regulations promulgated thereunder, we will, to the extent lawful:

The paying agent will promptly remit to each holder of Notes properly tendered the purchase price for the Notes, and the trustee will promptly authenticate and mail (or cause to be transferred by book-entry) to each holder a new Note equal in principal amount to any unpurchased portion of any Notes surrendered; provided, however, that each new Note will be in a minimum principal amount of $2,000 or an integral multiple of $1,000 in excess thereof.

We will not be required to make an offer to repurchase the Notes upon a Change of Control Repurchase Event if a third party makes an offer in the manner, at the times and otherwise in compliance with the requirements for an offer made by us and such third party purchases all Notes properly tendered and not withdrawn under its offer.

The source of funds that will be required to repurchase Notes in the event of a Change of Control Repurchase Event will be our available cash or cash generated from our operations or other potential sources, including funds provided by a purchaser in the Change of Control transaction, borrowings, sales of assets or sales of equity. We cannot assure you that sufficient funds from such sources will be available at the time of any Change of Control Repurchase Event to make required repurchases of Notes tendered. The terms of certain of our and our subsidiaries' financing arrangements provide that certain change of control events will constitute an event of default thereunder entitling the lenders to accelerate any indebtedness outstanding under our and our subsidiaries' financing arrangements at that time and to terminate the financing arrangements. See "Management's Discussion and Analysis of Financial Condition and Results of Operations-Financial Condition, Liquidity and Capital Resources" in our most recent Annual Report on Form 10-K and our most recent Quarterly Reports on Form 10-Q for a general discussion of our and our subsidiaries' indebtedness, which are incorporated by reference into this prospectus supplement. Our and our subsidiaries' future financing arrangements may contain

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similar restrictions and provisions. If the holders of the Notes exercise their right to require us to repurchase Notes upon a Change of Control Repurchase Event, the financial effect of this repurchase could cause a default under our and our subsidiaries' future financing arrangements, even if the Change of Control Repurchase Event itself would not cause a default. It is possible that we will not have sufficient funds at the time of the Change of Control Repurchase Event to make the required repurchase of the Notes and/or our and our subsidiaries' other debt. See "Risk Factors-Risks Related to the Notes-We may not be able to repurchase the Notes upon a Change of Control Repurchase Event" in this prospectus supplement for more information.

The definition of "Change of Control" includes a phrase relating to the direct or indirect sale, transfer, conveyance or other disposition of "all or substantially all" of our properties or assets and those of our subsidiaries taken as a whole. Although there is a limited body of case law interpreting the phrase "substantially all," there is no precise, established definition of the phrase under applicable law. Accordingly, the ability of a holder of Notes to require us to repurchase the Notes as a result of a sale, transfer, conveyance or other disposition of less than all of our assets and the assets of our subsidiaries taken as a whole to another person or group may be uncertain.

For purposes of the Notes:

"Below Investment Grade Rating Event" means the Notes are downgraded below Investment Grade by both of the Rating Agencies on any date from the date of the public notice of an arrangement that results in a Change of Control until the end of the 60-day period following public notice of the occurrence of a Change of Control (which period will be extended so long as the rating of the Notes is under publicly announced consideration for possible downgrade by either of the Rating Agencies); provided, however, that a Below Investment Grade Rating Event otherwise arising by virtue of a particular reduction in rating will not be deemed to have occurred in respect of a particular Change of Control (and thus will not be deemed a Below Investment Grade Rating Event for purposes of the definition of Change of Control Repurchase Event hereunder) if the Rating Agencies making the reduction in rating to which this definition would otherwise apply do not announce or publicly confirm or inform the trustee in writing at its request that the reduction was the result, in whole or in part, of any event or circumstance comprised of or arising as a result of, or in respect of, the applicable Change of Control (whether or not the applicable Change of Control will have occurred at the time of the Below Investment Grade Rating Event).

"Change of Control" means the occurrence of any of the following:

"Change of Control Repurchase Event" means the occurrence of a Change of Control and a Below Investment Grade Rating Event.

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"Controlled Subsidiary" means any subsidiary of Carlyle Secured Lending, Inc., 50% or more of the outstanding equity interests of which are owned by Carlyle Secured Lending, Inc. and its direct or indirect subsidiaries and of which Carlyle Secured Lending, Inc. possesses, directly or indirectly, the power to direct or cause the direction of the management or policies, whether through the ownership of voting equity interests, by agreement or otherwise.

"Fitch" means Fitch Ratings, Inc., or any successor thereto.

"Investment Grade" means a rating of BBB- or better by Fitch (or its equivalent under any successor rating categories of Fitch) and Baa3 or better by Moody's (or its equivalent under any successor rating categories of Moody's) (or, in each case, if such Rating Agency ceases to rate the Notes for reasons outside of our control, the equivalent investment grade credit rating from any Rating Agency selected by us as a replacement Rating Agency).

"Moody's" means Moody's Investors Service or any successor thereto.

"Permitted Holders" means (i) us, (ii) one or more of our Controlled Subsidiaries and (iii) the Investment Adviser, any affiliate of the Investment Adviser or any entity that is managed by the Adviser that is organized under the laws of a jurisdiction located in the United States and in the business of managing or advising clients.

"Rating Agency" means:

"Voting Stock" as applied to stock of any person, means shares, interests, participations or other equivalents in the equity interest (however designated) in such person having ordinary voting power for the election of a majority of the directors (or the equivalent) of such person, other than shares, interests, participations or other equivalents having such power only by reason of the occurrence of a contingency.

Covenants

In addition to the covenants described in the base indenture, the following covenants will apply to the Notes. To the extent of any conflict or inconsistency between the base indenture and the following covenants, the following covenants will govern:

Merger, Consolidation or Sale of Assets

The indenture will provide that we will not merge or consolidate with or into any other person (other than a merger of a wholly owned subsidiary into us), or sell, transfer, lease, convey or otherwise dispose of all or substantially all our property (provided, however, that, for the avoidance of doubt, a pledge of assets pursuant to any secured debt instrument of Carlyle Secured Lending, Inc. or its Controlled Subsidiaries will not be deemed to be any such sale, transfer, lease, conveyance or disposition) in any one transaction or series of related transactions unless:

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For the purposes of this covenant, the sale, transfer, lease, conveyance or other disposition of all the property of one or more of our subsidiaries, which property, if held by us instead of such subsidiaries, would constitute all or substantially all of our property on a consolidated basis, will be deemed to be the transfer of all or substantially all of our property.

Although there is a limited body of case law interpreting the phrase "substantially all," there is no precise established definition of the phrase under applicable law. Accordingly, in certain circumstances there may be a degree of uncertainty as to whether a particular transaction would involve "all or substantially all" of the properties or assets of a person. As a result, it may be unclear as to whether the merger, consolidation or sale of assets covenant would apply to a particular transaction as described above absent a decision by a court of competent jurisdiction. Although these types of transactions may be permitted under the indenture, certain of the foregoing transactions could constitute a Change of Control that results in a Change of Control Repurchase Event permitting each holder to require us to repurchase the Notes of such holder as described above.

An assumption by any person of obligations under the Notes and the indenture might be deemed for U.S. federal income tax purposes to be an exchange of the Notes for new Notes by the holders thereof, resulting in recognition of gain or loss for such purposes and possibly other adverse tax consequences to the holders. Holders should consult their own tax advisors regarding the tax consequences of such an assumption.

Other Covenants

Events of Default

Each of the following will be an event of default for the Notes:

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If an event of default occurs and is continuing, then and in every such case (other than an event of default specified in item (6) above) the trustee or the holders of at least 25% in principal amount of the Notes may declare the entire principal amount of the outstanding Notes to be due and payable immediately, by a notice in writing to us (and to the trustee if given by the holders), and upon any such declaration such principal or specified portion thereof will become immediately due and payable. Notwithstanding the foregoing, in the case of the events of bankruptcy, insolvency or reorganization described in item (6) above, 100% of the principal of and accrued and unpaid interest on the Notes will automatically become due and payable.

At any time after a declaration of acceleration with respect to the Notes has been made and before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding Notes, by written notice to us and the trustee, may rescind and annul such declaration and its consequences if (i) we have paid or deposited with the trustee a sum sufficient to pay all overdue installments of interest, if any, on all outstanding Notes, the principal of (and premium, if any, on) all outstanding Notes that have become due otherwise than by such declaration of acceleration and interest thereon at the rate or rates borne by or provided for in such Notes, to the extent that payment of such interest is lawful interest upon overdue installments of interest at the rate or rates borne by or provided for in such Notes, and all sums paid or advanced by the trustee and the reasonable compensation, expenses, disbursements and advances of the trustee, its agents and counsel, and (ii) all events of default with respect to the Notes, other than the nonpayment of the principal of (or premium, if any, on) or interest on such Notes that have become due solely by such declaration of acceleration, have been cured or waived. No such rescission will affect any subsequent default or impair any right consequent thereon.

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No holder of Notes will have any right to institute any proceeding, judicial or otherwise, with respect to the indenture, or for the appointment of a receiver or trustee, or for any other remedy under the indenture, unless:

Notwithstanding any other provision in the indenture, the holder of any Note will have the right, which is absolute and unconditional, to receive payment of the principal of (and premium, if any, on) and interest, if any, on such Note on the stated maturity or maturity expressed in such Note (or, in the case of redemption, on the redemption date or, in the case of repayment at the option of the holders, on the repayment date) and to institute suit for the enforcement of any such payment, and such rights will not be impaired without the consent of such holder.

The trustee will be under no obligation to exercise any of the rights or powers vested in it by the indenture at the request or direction of any of the holders of the Notes unless such holders have offered to the trustee security or indemnity satisfactory to the trustee against the costs, expenses and liabilities which might be incurred by it in compliance with such request or direction. Subject to the foregoing, the holders of a majority in principal amount of the outstanding Notes will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to the Notes, provided that (i) such direction may not be in conflict with any rule of law or with the indenture, (ii) the trustee may take any other action deemed proper by the trustee that is not inconsistent with such direction and (iii) the trustee need not take any action that it determines in good faith may involve it in personal liability or be unjustly prejudicial to the holders of Notes not consenting.

The holders of not less than a majority in principal amount of the outstanding Notes may on behalf of the holders of all of the Notes waive any past default under the indenture with respect to the Notes and its consequences, except a default (i) in the payment of (or premium, if any, on) or interest, if any, on any Note, or (ii) in respect of a covenant or provision of the indenture which cannot be modified or amended without the consent of the holder of each outstanding Note affected. Upon any such waiver, such default will cease to exist, and any event of default arising therefrom will be deemed to have been cured, for every purpose, but no such waiver may extend to any subsequent or other default or event of default or impair any right consequent thereto.

We are required to deliver to the trustee, within 120 days after the end of each fiscal year, an officers' certificate as to the knowledge of the signers whether we are in default in the performance of any of the terms, provisions or conditions of the indenture.

Within 90 days after the occurrence of any default under the indenture with respect to the Notes, the trustee must transmit notice of such default known to the trustee, unless such default has been cured or waived; provided, however, that, except in the case of a default in the payment of the principal of (or premium, if any, on) or interest, if any, on any Note, the trustee will be protected in withholding such notice if and so long as the board of directors, the executive committee or a trust committee of directors and/or officers of the trustee in good faith determines that withholding of such notice is in the interest of the holders of the Notes.

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Satisfaction and Discharge

We may satisfy and discharge our obligations under the indenture by delivering to the security registrar for cancellation all outstanding Notes or by depositing with the trustee or delivering to the holders, as applicable, after the Notes have become due and payable, or otherwise, moneys sufficient to pay all of the outstanding Notes and paying all other sums payable under the indenture by us. Such discharge is subject to terms contained in the indenture.

Defeasance

In addition, the Notes are subject to defeasance and covenant defeasance, in each case, in accordance with the terms of the indenture.

Covenant Defeasance

If certain conditions are satisfied, we can make the deposit described below and be released from some of the restrictive covenants in the indenture under which the Notes were issued. This is called "covenant defeasance." In that event, you would lose the protection of those restrictive covenants but would gain the protection of having money and government securities set aside in trust to repay your Notes. In order to achieve covenant defeasance, we must do the following:

If we accomplished covenant defeasance, you can still look to us for repayment of the Notes if there were a shortfall in the trust deposit or the trustee is prevented from making payment. For example, if one of the remaining Events of Default occurred (such as our bankruptcy) and the Notes became immediately due and payable, there might be a shortfall. Depending on the event causing the default, you may not be able to obtain payment of the shortfall.

Legal Defeasance

If there is a change in U.S. federal income tax law, as described below, we can legally release ourselves from all payment and other obligations on the Notes (called "defeasance" or "legal defeasance") if we put in place the following other arrangements for you to be repaid:

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If we ever accomplished legal defeasance, as described above, you would have to rely solely on the trust deposit for repayment of the Notes. You could not look to us for repayment in the unlikely event of any shortfall. Conversely, the trust deposit would most likely be protected from claims of our lenders and other creditors if we ever became bankrupt or insolvent.

Trustee

The U.S. Bank Trust Company, National Association (as successor to The Bank Of New York Mellon Trust Company, N.A.) is the trustee, security registrar and paying agent. U.S. Bank Trust Company, National Association, in each of its capacities, including without limitation as trustee, security registrar and paying agent, assumes no responsibility for the accuracy or completeness of the information concerning us or our affiliates or any other party contained in this document or the related documents or for any failure by us or any other party to disclose events that may have occurred and may affect the significance or accuracy of such information, or for any information provided to it by us, including but not limited to settlement amounts and any other information. U.S. Bank Trust Company, National Association's address is 100 Wall Street 6th Floor, New York, New York 10005. We may maintain banking relationships in the ordinary course of business with the trustee and its affiliates.

Governing Law

The indenture provides that it and the Notes will be governed by and construed in accordance with the laws of the State of New York, without regard to principles of conflicts of laws that would cause the application of laws of another jurisdiction.

Book-Entry, Settlement and Clearance

Global Notes

The Notes will be initially issued in the form of one or more registered Notes in global form (the "Global Note"). Upon issuance, the Global Note will be deposited with the trustee as custodian for DTC and registered in the name of Cede & Co., as nominee of DTC.

Ownership of beneficial interests in a Global Note will be limited to persons who have accounts with DTC, Euroclear Bank S.A./N.V. ("Euroclear") or Clearstream Banking S.A. ("Clearstream") or DTC, Euroclear or Clearstream participants or persons who hold interests through DTC, Euroclear or Clearstream participants. We expect that under procedures established by DTC:

Beneficial interests in Global Notes may not be exchanged for Notes in physical, certificated form except in the limited circumstances described below.

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Book-Entry Procedures for Global Notes

All interests in the Global Notes will be subject to the operations and procedures of DTC. We provide the following summary of those operations and procedures solely for the convenience of investors. The operations and procedures of DTC are controlled by that settlement system and may be changed at any time. Neither we nor the underwriters are responsible for those operations or procedures.

DTC has advised us that it is:

DTC was created to hold securities for its participants and to facilitate the clearance and settlement of securities transactions between its participants through electronic book-entry changes to the accounts of its participants. DTC's participants include securities brokers and dealers, including the underwriters; banks and trust companies; clearing corporations and other organizations. Indirect access to DTC's system is also available to others such as banks, brokers, dealers and trust companies; these indirect participants clear through or maintain a custodial relationship with a DTC participant, either directly or indirectly. Investors who are not DTC participants may beneficially own securities held by or on behalf of DTC only through DTC participants or indirect participants in DTC.

Euroclear and Clearstream hold securities for participating organizations. They also facilitate the clearance and settlement of securities transactions between their respective participants through electronic book-entry changes in the accounts of such participants. Euroclear and Clearstream provide various services to their participants, including the safekeeping, administration, clearance, settlement, lending and borrowing of internationally traded securities. Euroclear and Clearstream interface with domestic securities markets. Euroclear and Clearstream participants are financial institutions such as underwriters, securities brokers and dealers, banks, trust companies and certain other organizations. Indirect access to Euroclear and Clearstream is also available to others such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a Euroclear and Clearstream participant, either directly or indirectly.

So long as the Notes are held in global form, Euroclear, Clearstream and/or DTC, as applicable, (or their respective nominees) will be considered the sole holders of Global Notes for all purposes under the indenture. As such, participants must rely on the procedures of Euroclear, Clearstream and/or DTC and indirect participants must rely on the procedures of Euroclear, Clearstream and/ or DTC and the participants through which they own interests in the Notes, or "Book-Entry Interests," in order to exercise any rights of holders under the indenture.

So long as DTC, Euroclear or Clearstream's nominee is the registered owner of a Global Note, that nominee will be considered the sole owner or holder of the Notes represented by that Global Note for all purposes under the indenture. Except as provided below, owners of beneficial interests in a Global Note:

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As a result, each investor who owns a beneficial interest in a Global Note must rely on the procedures of DTC, Euroclear or Clearstream to exercise any rights of a holder of Notes under the indenture (and, if the investor is not a participant or an indirect participant in DTC, Euroclear or Clearstream, on the procedures of the DTC, Euroclear or Clearstream participant through which the investor owns its interest).

Payments of principal and interest with respect to the Notes represented by a Global Note will be made by the trustee to DTC, Euroclear or Clearstream's nominee as the registered holder of the Global Note. Neither we nor the trustee will have any responsibility or liability for the payment of amounts to owners of beneficial interests in a Global Note, for any aspect of the records relating to or payments made on account of those interests by DTC, Euroclear or Clearstream, or for maintaining, supervising or reviewing any records of DTC, Euroclear or Clearstream relating to those interests.

Payments by participants and indirect participants in DTC, Euroclear or Clearstream to the owners of beneficial interests in a Global Note will be governed by standing instructions and customary industry practice and will be the responsibility of those participants or indirect participants and DTC, Euroclear or Clearstream.

Transfers between participants in DTC, Euroclear or Clearstream will be effected under DTC, Euroclear or Clearstream's procedures and will be settled in same-day funds.

Cross-market transfers of beneficial interests in Global Notes between DTC participants, on the one hand, and Euroclear or Clearstream participants, on the other hand, will be effected within DTC through the DTC participants that are acting as depositaries for Euroclear and Clearstream. To deliver or receive an interest in a Global Note held in a Euroclear or Clearstream account, an investor must send transfer instructions to Euroclear or Clearstream, as the case may be, under the rules and procedures of that system and within the established deadlines of that system. If the transaction meets its settlement requirements, Euroclear or Clearstream, as the case may be, will send instructions to its DTC depositary to take action to effect final settlement by delivering or receiving interests in the relevant Global Notes in DTC, and making or receiving payment under normal procedures for same-day funds settlement applicable to DTC. Euroclear and Clearstream participants may not deliver instructions directly to the DTC depositaries that are acting for Euroclear or Clearstream.

Because the settlement of cross-market transfers takes place during New York business hours, DTC participants may employ their usual procedures for sending securities to the applicable DTC participants acting as depositaries for Euroclear and Clearstream. The sale proceeds will be available to the DTC participant seller on the settlement date. Thus, to a DTC participant, a cross-market transaction will settle no differently from a trade between two DTC participants. Because of time zone differences, the securities account of a Euroclear or Clearstream participant that purchases an interest in a Global Note from a DTC participant will be credited on the business day for Euroclear or Clearstream immediately following the DTC settlement date. Cash received in Euroclear or Clearstream from the sale of an interest in a Global Note to a DTC participant will be reflected in the account of the Euroclear of Clearstream participant the following business day, and receipt of the cash proceeds in the Euroclear or Clearstream participant's account will be back-valued to the date on which settlement occurs in New York. DTC, Euroclear and Clearstream have agreed to the above procedures to facilitate transfers of interests in the Global Notes among participants in those settlement systems. However, the settlement systems are not obligated to perform these procedures and may discontinue or change these procedures at any time. Neither we nor the trustee will have any responsibility or liability for the performance by DTC, Euroclear or Clearstream or their participants or indirect participants of their obligations under the rules and procedures governing their operations, including maintaining, supervising or reviewing the records relating to, or payments made on account of, beneficial ownership interests in Global Notes.

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Certificated Notes

Notes in physical, certificated form will be issued and delivered to each person that DTC, Euroclear or Clearstream identifies as a beneficial owner of the related Notes only if:

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CERTAIN UNITED STATES FEDERAL INCOME TAX CONSEQUENCES

This section describes the material United States federal income tax consequences of owning the Notes. It applies to you only if you acquire the Notes in the offering at the public offering price printed on the cover of this prospectus supplement and you hold your Notes as capital assets for tax purposes. This section addresses only United States federal income taxation and does not discuss all of the tax consequences that may be relevant to you in light of your individual circumstances, including foreign, state or local tax consequences, and tax consequences arising under the Medicare contribution tax on net investment income or the alternative minimum tax. This section does not apply to you if you are a member of a class of holders subject to special rules, such as:

This section is based on the Code, its legislative history, existing and proposed regulations under the Code, published rulings and court decisions, all as currently in effect. These laws are subject to change, possibly on a retroactive basis.

If an entity or arrangement that is treated as a partnership for United States federal income tax purpose holds the Notes, the United States federal income tax treatment of a partner will generally depend on the status of the partner and the tax treatment of the partnership. A partner in a partnership holding the Notes should consult its tax advisor with regard to the United States federal income tax treatment of an investment in the Notes.

United States Holders

This subsection describes the tax consequences to a United States holder. You are a United States holder if you are a beneficial owner of a Note and you are, for United States federal income tax purposes:

If you are not a United States holder, this subsection does not apply to you and you should refer to "Non-United States Holders" below.

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Payments of Interest. You will be taxed on interest on your Note as ordinary income at the time you receive the interest or when it accrues, depending on your method of accounting for tax purposes.

Purchase, Sale and Retirement of the Notes. Your tax basis in your Note generally will be its cost. You will generally recognize capital gain or loss on the sale or retirement of your Note equal to the difference between the amount you realize on the sale or retirement, excluding any amounts attributable to accrued but unpaid interest (which will be treated as interest payments), and your tax basis in your Note. Capital gain of a noncorporate United States holder is generally taxed at preferential rates where the property is held for more than one year. The deductibility of capital losses is subject to limitations under the Code.

Non-United States Holders

This subsection describes the tax consequences to a Non-United States holder. You are a Non-United States holder if you are the beneficial owner of a Note and are not a United States holder nor an entity or arrangement that is treated as a partnership for United States federal income tax purposes.

If you are a United States holder, this subsection does not apply to you.

Interest. Subject to the discussions of FATCA withholding and backup withholding below, interest on a Note that is not effectively connected with your conduct of a trade or business in the United States will generally be exempt from United States federal income and withholding tax under the "portfolio interest exemption," provided that (i) you do not, actually or constructively, own stock possessing 10% or more of the total voting power of the Company's outstanding stock, (ii) you are not a controlled foreign corporation that is related to the Company, actually or constructively through sufficient ownership of the Company's stock and (iii) either (a) you provide to the applicable withholding agent an Internal Revenue Service ("IRS") Form W-8BEN or W-8BEN-E (or other applicable form), signed under penalties of perjury, that includes your name and address and that certifies your non-United States status in compliance with applicable law and regulations, or (b) a securities clearing organization, bank or other financial institution that holds customers' securities in the ordinary course of its trade or business provides a statement to the applicable withholding agent under penalties of perjury on which it certifies that an applicable IRS Form W-8BEN or W-8BEN-E (or other applicable form) has been received by it from you or a qualifying intermediary and furnishes a copy to the applicable withholding agent. This certification requirement may be satisfied with other documentary evidence in the case of a Note held in an offshore account or through certain foreign intermediaries. The applicable withholding agent for purposes of the certification requirement described above is generally the last U.S. payor (or a non-U.S. payor that is a qualified intermediary or a U.S. branch of a foreign person) in the chain of payment before payment to you.

If you cannot satisfy the requirements of the portfolio interest exemption described above, then payments of interest made to you generally will be subject to United States federal withholding tax at the rate of 30%, unless either (i) you provide the applicable withholding agent with a properly executed IRS Form W-8BEN or W-8BEN-E establishing an exemption from or reduction of the withholding tax under the benefit of an applicable income tax treaty or (ii) the interest is effectively connected with your conduct of a trade or business in the United States and you provide an appropriate statement to that effect on a properly completed and duly executed IRS Form W-8ECI.

If you engaged in a trade or business in the United States and interest on a Note is effectively connected with the conduct of that trade or business (and, if required by an applicable income tax treaty, you maintain a permanent establishment in the United States to which such interest is attributable), you will be subject to United States federal income tax on such interest on a net income basis in generally the same manner as a United States holder, unless an applicable income tax treaty provides otherwise. If you are a non-United States holder that is treated as a foreign corporation for United States federal income tax purposes, you may also be subject to a branch profits tax at a 30% rate (or lower applicable treaty rate) on your effectively connected earnings and profits, subject to adjustments.

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Purchase, Sale and Retirement of the Notes. Subject to the discussion of backup withholding below, you generally will not be subject to United States federal income or withholding tax on any gain realized on a sale, exchange, redemption, retirement or other taxable disposition of a Note (other than any amount representing accrued but unpaid interest, which will be treated as interest and will generally be subject to the rules discussed above under "Interest") unless:

If you are described in the first bullet point above, you generally will be subject to United States federal income tax at a flat rate of 30% (unless a lower treaty rate applies) on your gain from the disposition, which may be offset by certain United States-source capital losses. If you are described in the second bullet point above, you will be subject to United States federal income tax on such gain on a net income basis in generally the same manner as a United States holder, unless an applicable income tax treaty provides otherwise. If you are a non-United States holder that is treated as a foreign corporation for United States federal income tax purposes, you may also be subject to a branch profits tax at a 30% rate (or lower applicable treaty rate) on your effectively connected earnings and profits, subject to adjustments.

Estate Tax. A Note held by an individual who at death is not a citizen or resident of the United States would not be includible in the individual's gross estate for United States federal estate tax purposes if:

Foreign Account Tax Compliance Withholding

Pursuant to sections 1471 through 1474 of the Code, commonly known as the Foreign Account Tax Compliance Act ("FATCA"), a 30% withholding tax ("FATCA withholding") may be imposed on certain payments to you or to certain foreign financial institutions, investment funds and other non-U.S. persons receiving payments on your behalf if you or such persons fail to comply with certain information reporting requirements. Payments of interest that you receive in respect of the Notes generally will be subject to this withholding if you are a Non-United States holder and you fail to comply with such reporting requirements or if you hold Notes through a non-U.S. person (e.g., a foreign bank or broker) that fails to comply with these reporting requirements and certain withholding requirements (even if payments to you would not otherwise have been subject to FATCA withholding). You should consult your own tax advisors regarding the relevant U.S. law and other official guidance on FATCA withholding.

Depending on your circumstances, you may be entitled to a refund or credit in respect of some or all of this withholding. However, even if you are entitled to have any such withholding refunded, the required procedures could be cumbersome and significantly delay your receipt of any amounts withheld.

Backup Withholding and Information Reporting

In general, if you are a United States holder, the applicable withholding agent will be required to report to the IRS all payments of principal and interest on your Note. In addition, the applicable withholding agent will be required to report to the IRS any payment of proceeds of the sale of your Note before maturity within the United

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States (unless you are an exempt recipient and certify your status as such, if required to do so). Additionally, backup withholding would apply to any payments if you fail to provide an accurate taxpayer identification number, or (in the case of interest payments) you are notified by the IRS that you have failed to report all interest and dividends required to be shown on your federal income tax returns.

The amount of interest that we pay to any Non-United States holder on the Notes will be reported to the Non-United States holder and to the IRS annually on an IRS Form 1042-S, regardless of whether any tax was actually withheld. Copies of these information returns may also be made available under the provisions of a specific income tax treaty or agreement to the tax authorities of the country in which the Non-United States holder resides. In general, payment of the proceeds from the sale of Notes effected at a foreign office of a foreign broker will not be subject to information reporting or backup withholding. However, a sale effected at a foreign office of a broker could be subject to information reporting in the same manner as a sale within the United States (and in certain cases may be subject to backup withholding as well) if (i) the broker has certain connections to the United States, (ii) the proceeds or confirmation are sent to the United States or (iii) the sale has certain other specified connections with the United States, unless the Non-United States holder provides to such broker a withholding certificate or other documentary evidence establishing that such holder is not a United Stats holder and such broker does not have actual knowledge or reason to know that such withholding certificate or documentary evidence is false, or the Non-United States holder is an exempt recipient eligible for an exemption from information reporting and certifies its status as such, if required to do so.

You generally may obtain a refund of any amounts withheld under the backup withholding rules that exceed your income tax liability by filing a refund claim with the IRS.

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UNDERWRITING

J.P. Morgan Securities LLC, Barclays Capital Inc., BofA Securities, Inc. and Morgan Stanley & Co. LLC are acting as representatives of each of the several underwriters named below. Subject to the terms and conditions set forth in an underwriting agreement among us, the Investment Adviser, the Administrator and the underwriters, we have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase from us, the aggregate principal amount of Notes set forth opposite its name below.

Subject to the terms and conditions set forth in the underwriting agreement, the underwriters have agreed, severally and not jointly, to purchase all of the Notes sold under the underwriting agreement if any of these Notes are purchased. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the nondefaulting underwriters may be increased or the underwriting agreement may be terminated.

We, the Investment Adviser and the Administrator have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the "Securities Act"), or to contribute to payments the underwriters may be required to make in respect of those liabilities.

The underwriters are offering the Notes, subject to prior sale, when, as and if issued to and accepted by them, subject to approval of legal matters by their counsel, including the validity of the Notes, and other conditions contained in the underwriting agreement, such as the receipt by the underwriters of officers' certificates and legal opinions. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

Commissions and Discounts

The following table shows the per Note and total underwriting discount that we are to pay to the underwriters in connection with this offering.

The underwriters propose to offer some of the Notes to the public at the public offering price set forth on the cover page of this prospectus supplement, and some of the Notes to certain other Financial Industry Regulatory Authority, or FINRA, members at the public offering price less a concession not in excess of % of the aggregate principal amount of the Notes. The underwriters may allow, and the dealers may reallow, a discount not in excess of % of the aggregate principal amount of the Notes. After the initial offering of the Notes to the public, the public offering price and such concessions may be changed. No such change shall change the amount of proceeds to be received by us as set forth on the cover page of this prospectus supplement.

The expenses of the offering, not including the underwriting discount, are estimated at $  and are payable by us.

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No Sales of Similar Securities

Subject to certain exceptions, we have agreed not to directly or indirectly, offer, pledge, sell, contract to sell, grant any option for the sale of or otherwise transfer or dispose of any debt securities issued or guaranteed by us or any securities convertible into or exercisable or exchangeable for debt securities issued or guaranteed by us or file any registration statement under the Securities Act with respect to any of the foregoing through the closing date of this offering without first obtaining the written consent of the representatives. This consent may be given at any time without public notice.

Listing

The Notes are a new issue of securities with no established trading market. The Notes will not be listed on any securities exchange or quoted on any automated dealer quotation system.

We have been advised by certain of the underwriters that they currently intend to make a market in the Notes after completion of the offering as permitted by applicable laws and regulations. The underwriters are not obligated, however, to make a market in the Notes and any such market-making may be discontinued at any time in the sole discretion of the underwriters without any notice. Accordingly, no assurance can be given as to the liquidity of, or development of a public trading market for, the Notes. If an active public trading market for the Notes does not develop, the market price and liquidity of the Notes may be adversely affected.

Price Stabilization, Short Positions

In connection with the offering, the underwriters may purchase and sell Notes in the open market. These transactions may include over-allotment, covering transactions and stabilizing transactions. Over-allotment involves sales of Notes in excess of the aggregate principal amount of Notes to be purchased by the underwriters in the offering, which creates a short position for the underwriters. Covering transactions involve purchases of the Notes in the open market after the distribution has been completed in order to cover short positions. Stabilizing transactions consist of certain bids or purchases of Notes made for the purpose of preventing or retarding a decline in the market price of the Notes while the offering is in progress.

The underwriters also may impose a penalty bid. This occurs when a particular underwriter repays to the underwriters a portion of the underwriting discount received by it because the representatives has repurchased Notes sold by or for the account of such underwriter in stabilizing or short covering transactions.

Any of these activities may cause the price of the Notes to be higher than the price that otherwise would exist in the open market in the absence of such transactions. These transactions may be effected in the over-the-counter market or otherwise and, if commenced, may be discontinued at any time without any notice relating thereto.

Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of the Notes. In addition, neither we nor any of the underwriters make any representation that the representatives will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

Other Relationships

The underwriters and their respective affiliates are full service financial institutions engaged in various activities, which may include sales and trading, commercial and investment banking, advisory, investment management, investment research, principal investment, hedging, market making, brokerage, valuation services and other financial and non-financial activities and services. Certain of the underwriters and their respective affiliates have provided, currently provide, and may in the future provide, a variety of these services to us and to persons and entities with relationships with us, for which they received or will receive customary fees and expenses. For example, certain of the underwriters and their affiliates were underwriters in connection with the

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Company's initial public offering and our subsequent debt and equity offerings, for which they received customary fees. Additionally, affiliates of certain underwriters are lenders under the credit facilities of the Company and its subsidiaries.

In the ordinary course of their various business activities, the underwriters and their respective affiliates, officers, directors and employees may purchase, sell or hold a broad array of investments and actively traded securities, derivatives, loans, commodities, currencies, credit default swaps and other financial instruments for their own account and for the accounts of their customers, and such investment and trading activities may involve or relate to assets, securities or instruments of us (directly, as collateral securing other obligations or otherwise) or persons and entities with relationships with us. Certain of the underwriters and their affiliates that have a lending relationship with us routinely hedge their credit exposure to us consistent with their customary risk management policies. Typically, such underwriters and their affiliates would hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities, including potentially the Notes offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the Notes offered hereby. The underwriters and their respective affiliates may also communicate independent investment recommendations, market color or trading ideas or publish or express independent research views in respect of such assets, securities or instruments and may at any time hold, or recommend to clients that they should acquire, long or short positions in such assets, securities and instruments.

The net proceeds of this offering may be used to pay down a portion of the outstanding indebtedness under the Credit Facility. Affiliates of certain of the underwriters are lenders under the Credit Facility. Accordingly, affiliates of certain of the underwriters may receive more than 5% of the proceeds of this offering to the extent such proceeds are used to repay or repurchase outstanding indebtedness under the Credit Facility.

Settlement

We expect that delivery of the Notes will be made to investors on or about    , 2024, which will be the business day following the date hereof. Under Rule 15c6-1 under the Exchange Act, trades in the secondary market are required to settle in one business day, unless the parties to any such trade expressly agree otherwise. Accordingly, purchasers who wish to trade Notes prior to the date that is one business prior to delivery of the Notes will be required by virtue of the fact that the Notes initially settle in T+ , to specify an alternate settlement arrangement at the time of any such trade to prevent a failed settlement. Purchasers of the Notes who wish to trade the Notes prior to the date that is one business prior to delivery of the Notes should consult their own advisor.

Principal Business Addresses

The principal business address of J.P. Morgan Securities LLC is 383 Madison Avenue, New York, NY 10179. The principal business address of Barclays Capital Inc. is 745 Seventh Avenue, New York, NY 10019. The principal business address of BofA Securities, Inc. is One Bryant Park, New York, NY 10036. The principal business address of Morgan Stanley & Co. LLC is 1585 Broadway, New York, NY 10036.

Disclaimers About Non-US Jurisdictions

Notice to Prospective Investors in the European Economic Area

The Notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the European Economic Area ("EEA"). For the purposes of this provision:

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Consequently, no key information document required by Regulation (EU) No 1286/2014 (as amended, the "PRIIPs Regulation") for offering or selling the Notes or otherwise making them available to retail investors in the EEA has been prepared and therefore offering or selling the Notes or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation. This prospectus supplement has been prepared on the basis that any offer of Notes in any member state of the EEA will be made pursuant to an exemption under the Prospectus Regulation from the requirement to publish a prospectus for offers of Notes. This prospectus supplement is not a prospectus for the purposes of the Prospectus Regulation.

Notice to Prospective Investors in the United Kingdom

The Notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the United Kingdom. For the purposes of this provision:

Consequently, no key information document required by Regulation (EU) No 1286/2014 as it forms part of domestic law by virtue of the EUWA (the "UK PRIIPs Regulation") for offering or selling the Notes or otherwise making them available to retail investors in the UK has been prepared and therefore offering or selling the Notes or otherwise making them available to any retail investor in the UK may be unlawful under the UK PRIIPs Regulation. This prospectus supplement has been prepared on the basis that any offer of Notes in the UK will be made pursuant to an exemption under the UK Prospectus Regulation from the requirement to publish a prospectus for offers of Notes. This prospectus supplement is not a prospectus for the purposes of the UK Prospectus Regulation.

This prospectus supplement and any other material in relation to the Notes is only being distributed to, and is directed only at, persons in the United Kingdom who are "qualified investors" (as defined in the UK Prospectus Regulation who are also (i) investment professionals falling within Article 19(5) of the Financial

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Services and Markets Act 2000 (Financial Promotion) Order 2005 (as amended, the "Order"), or (ii) high net worth entities or other persons falling within Articles 49(2)(a) to (d) of the Order, or (iii) persons to whom it would otherwise be lawful to distribute it, all such persons together being referred to as "Relevant Persons". The Notes are only available to, and any invitation, offer or agreement to subscribe, purchase or otherwise acquire such Notes will be engaged in only with, Relevant Persons. This prospectus supplement and its contents are confidential and should not be distributed, published or reproduced (in whole or in part) or disclosed by any recipients to any other person in the United Kingdom. Any person in the United Kingdom that is not a Relevant Person should not act or rely on this prospectus supplement or its contents. The Notes are not being offered to the public in the United Kingdom.

In addition, in the United Kingdom, each underwriter has represented and agreed the Notes may not be offered other than by an underwriter that:

Notice to Prospective Investors in Canada

The Notes may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the Notes must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement and the accompanying prospectus (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser's province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser's province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

The Investment Adviser is not registered as an investment fund manager in any province or territory of Canada. Its head office is located in New York, New York in the United States. All or substantially all of its assets may be situated outside of Canada, and there may be difficulty for persons in Canada to enforce legal rights against it for that reason. The Investment Adviser has appointed 152928 Canada Inc. as its agent for service of process in Ontario and Quebec, whose address in Ontario is 5300 Commerce Court West, 199 Bay Street, Toronto, Ontario M5L 1B9 and whose address in Quebec is 1155 Rene-Levesque Blvd., 41st Floor, Montreal, Quebec H3B 3V2.

Notice to Prospective Investors in Israel

Sales of the Notes in Israel will be made through the underwriters and/or through an Israeli broker(s) engaged by them. The Notes will not be offered to an Israeli person unless such offeree is a "qualified investor"

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(as defined in the First Appendix to the Israeli Securities Law) who is not an individual (a "Qualified Israeli Investor") and who has (x) completed and signed a questionnaire regarding qualification as a Qualified Israel Investor and (y) certified that it has an exemption from Israeli withholding taxes on interest.

Notice to Prospective Investors in Hong Kong

The contents of this prospectus supplement have not been reviewed, approved or endorsed by any regulatory authority in Hong Kong. The Notes have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to "professional investors" as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance, or the professional investors; or (b) in other circumstances which do not result in the document being a "prospectus" as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the Notes has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to Notes which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors". This prospectus supplement is intended solely for the use of the person to whom it has been delivered for the purpose of evaluating a possible investment by the recipient in the Notes described herein, and is not to be reproduced or distributed to any other persons (other than professional advisors of the prospective investor receiving this prospectus supplement).

Notice to Prospective Investors in Singapore

This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the Notes may not be circulated or distributed, nor may the Notes be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor (as defined in Section 4A of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA")) under Section 274 of the SFA, (ii) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA, in each case subject to conditions set forth in the SFA.

Where the Notes are subscribed or purchased under Section 275 of the SFA by a relevant person which is a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor, the securities (as defined in Section 239(1) of the SFA) of that corporation shall not be transferable for 6 months after that corporation has acquired the Notes under Section 275 of the SFA except: (1) to an institutional investor under Section 274 of the SFA or to a relevant person (as defined in Section 275(2) of the SFA), (2) where such transfer arises from an offer in that corporation's securities pursuant to Section 275(1A) of the SFA, (3) where no consideration is or will be given for the transfer, (4) where the transfer is by operation of law, (5) as specified in Section 276(7) of the SFA, or (6) as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations 2005 of Singapore ("Regulation 32").

Where the Notes are subscribed or purchased under Section 275 of the SFA by a relevant person which is a trust (where the trustee is not an accredited investor (as defined in Section 4A of the SFA)) whose sole purpose is to hold investments and each beneficiary of the trust is an accredited investor, the beneficiaries' rights and interest (howsoever described) in that trust shall not be transferable for 6 months after that trust has acquired the Notes under Section 275 of the SFA except: (1) to an institutional investor under Section 274 of the SFA or to a relevant person (as defined in Section 275(2) of the SFA), (2) where such transfer arises from an offer that is

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made on terms that such rights or interest are acquired at a consideration of not less than S$200,000 (or its equivalent in a foreign currency) for each transaction (whether such amount is to be paid for in cash or by exchange of securities or other assets), (3) where no consideration is or will be given for the transfer, (4) where the transfer is by operation of law, (5) as specified in Section 276(7) of the SFA, or (6) as specified in Regulation 32.

Singapore Securities and Futures Act Product Classification: Solely for the purpose of its obligations pursuant to sections 309B(1)(a) and 309B(1)(c) of the SFA, the Company has determined, and hereby notifies all relevant persons (as defined in Section 309A of the SFA) that the Notes are "prescribed capital markets products" (as defined in the Securities and Futures (Capital Markets Products) Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA 04-N12: Notice on the Sale of Investment Products and MAS Notice FAA-N16: Notice on Recommendations on Investment Products).

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LEGAL MATTERS

Certain legal matters will be passed upon for us by Sullivan & Cromwell LLP. Certain matters of Maryland law, including the validity of the Notes to be issued in connection with this offering, will be passed upon for us by Venable LLP, Baltimore, Maryland. Certain legal matters will be passed upon for the underwriters by Ropes & Gray LLP.

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The financial statements and the senior securities table incorporated in the accompanying prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2023 have been so incorporated in reliance on the report of Ernst & Young LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

This prospectus supplement and the accompanying prospectus are part of a registration statement that we have filed with the SEC. We are allowed to "incorporate by reference" the information that we file with the SEC, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to comprise a part of this prospectus supplement and the accompanying prospectus, and later information that we file with the SEC prior to the completion of this offering will automatically update and, where applicable, supersede such information contained in this prospectus supplement or incorporated by reference therein.

We incorporate by reference in this prospectus supplement and the accompanying prospectus the documents listed below that have been previously filed with the SEC:

We also incorporate by reference into the prospectus additional documents that we may file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, from the date of this prospectus supplement until all of the securities offered by this prospectus supplement have been sold or the offering of these securities is otherwise terminated; provided, however, that information "furnished" under Item 2.02 or Item 7.01 of Form 8-K or other information "furnished" to the SEC which is not deemed filed shall not be deemed to be incorporated by reference in this prospectus supplement and in the accompanying prospectus. Any statement contained in any document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus supplement and the accompanying prospectus to the extent that a statement contained in this prospectus supplement, in the accompanying prospectus or in any other subsequently

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filed document which also is or is deemed to be incorporated by reference in this prospectus supplement modifies or supersedes such earlier statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement.

You may obtain copies of any of these filings from us as described below, through the SEC or through the SEC's website as described under "Where You Can Find More Information" in this prospectus supplement. Documents incorporated by reference are available without charge, excluding all exhibits unless an exhibit has been specifically incorporated by reference into the accompanying prospectus, by writing or calling our Investor Relations Department at the following address and telephone number:

Carlyle Secured Lending, Inc.

Investor Relations

One Vanderbilt Avenue

Suite 3400

New York, NY 10017

(212) 813-4900

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WHERE YOU CAN FIND MORE INFORMATION

This prospectus supplement and the accompanying prospectus constitute part of a registration statement on Form N-2 that we have filed with the SEC, together with any and all amendments and related exhibits under the Securities Act. This prospectus supplement and the accompanying prospectus do not contain all of the information set forth in the registration statement, some of which is contained in exhibits to the registration statement as permitted by the rules and regulations of the SEC. For further information with respect to us and the offering under this prospectus supplement and the accompanying prospectus, we refer you to the registration statement, including the exhibits filed as a part of, or incorporated by reference into, the registration statement. Statements contained in this prospectus supplement and the accompanying prospectus concerning the contents of any contract or any other document are not necessarily complete. If a contract or other document has been filed as an exhibit to the registration statement or otherwise incorporated by reference as an exhibit thereto, please see the copy of the contract or document that has been filed or incorporated by reference. Each statement in this prospectus supplement and the accompanying prospectus relating to a contract or document filed or incorporated by reference as an exhibit is qualified in all respects by such exhibit.

We file with or submit to the SEC annual, quarterly and current reports, proxy statements and other information meeting the informational requirements of the Exchange Act. This information is available free of charge on our website at http://carlylesecuredlending.com/. Except for the documents incorporated by reference into the accompanying prospectus, information contained on our website is not incorporated into this prospectus supplement or the accompanying prospectus and you should not consider such information to be part of reports, proxy and information statements and other information filed electronically by us with the SEC, which are available on the SEC's website free of charge at www.sec.gov. You can request a copy of any of our SEC filings, including those incorporated by reference herein or in the accompanying prospectus, at no cost, by writing or telephoning us at the address or telephone number above.

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PROSPECTUS

Carlyle Secured Lending, Inc.

Common Stock

Preferred Stock

Debt Securities

Subscription Rights

Warrants

Units

We operate as a specialty finance company that is a closed-end, externally managed, non-diversified management investment company, and have elected to be regulated as a business development company ("BDC") under the Investment Company Act of 1940, as amended. For U.S. federal income tax purposes, we have elected to be treated as a regulated investment company under Subchapter M of the Internal Revenue Code of 1986, as amended. Our investment objective is to generate current income and, to a lesser extent, capital appreciation primarily through assembling a portfolio of secured debt investments in U.S. middle market companies. Our core investment strategy focuses on lending to U.S. middle market companies, which we define as companies with approximately $25 million to $100 million of earnings before interest, taxes, depreciation and amortization, supported by financial sponsors. This core strategy is opportunistically supplemented with differentiated and complementary lending and investing strategies, which take advantage of the broad capabilities of Carlyle's Global Credit platform while offering risk-diversifying portfolio benefits. We seek to achieve our investment objective primarily through direct origination of secured debt instruments, including first lien senior secured loans (which may include stand-alone first lien loans, first lien/last out loans and "unitranche" loans) and second lien senior secured loans (collectively, "Middle Market Senior Loans"), with a minority of our assets invested in higher yielding investments (which may include unsecured debt, subordinated debt and investments in equities). The Middle Market Senior Loans are generally made to private U.S. middle market companies that are, in many cases, controlled by private equity firms. As of December 31, 2023, our investment portfolio consisted of 173 investments in 128 portfolio companies with an aggregate fair value of $1,842 million.

We are externally managed by our investment adviser, Carlyle Global Credit Investment Management L.L.C. (the "Investment Adviser"), a wholly-owned subsidiary of The Carlyle Group Inc. and an investment adviser registered under the Investment Advisers Act of 1940, as amended. Carlyle Global Credit Administration L.L.C. (the "Administrator") provides the administrative services necessary for the Company to operate. Both the Investment Adviser and the Administrator are wholly owned subsidiaries of Carlyle Investment Management L.L.C. ("CIM"), a wholly owned subsidiary of The Carlyle Group Inc. The Carlyle Group Inc. is a global alternative asset manager with $426 billion of assets under management as of December 31, 2023.

We may offer, from time to time, in one or more offerings or series, our common stock, preferred stock, debt securities, subscription rights to purchase shares of our common stock, warrants representing rights to purchase shares of our common stock, preferred stock or debt securities, or units comprised of any combination of the foregoing, which we refer to, collectively, as the "securities." The preferred stock, debt securities, subscription rights and warrants (including as part of a unit) offered hereby may be convertible or exchangeable into shares of our common stock. The securities may be offered at prices and on terms to be described in one or more supplements to this prospectus.

In the event we offer our common stock, the offering price per share of our common stock exclusive of any underwriting commissions or discounts will not be less than the net asset value per share of our common stock at the time we make the offering except (1) in connection with a rights offering to our existing stockholders, (2) with the consent of the majority of our voting securities and approval of our Board of Directors or (3) under such circumstances as the United States Securities and Exchange Commission, or the SEC, may permit.

The securities may be offered directly to one or more purchasers, including existing stockholders pursuant to subscriptions rights, or through agents designated from time to time by us, or to or through underwriters or dealers. Each prospectus supplement relating to an offering will identify any agents or underwriters involved in the sale of the securities, and will disclose any applicable purchase price, fee, discount or commissions arrangement between us and our agents or underwriters or among our underwriters or the basis upon which such amount may be calculated. See "Plan of Distribution." We may not sell any of the securities pursuant to this registration statement through agents, underwriters or dealers without delivery of this prospectus and a prospectus supplement describing the method and terms of the offering of such securities.

Our common stock is traded on The NASDAQ Global Select Market ("Nasdaq") under the symbol "CGBD" and our 8.20% notes due 2028 trade on Nasdaq under the ticker symbol "CGBDL." On April 25, 2024 the last reported sales price of our common stock on The Nasdaq Global Select Market was $16.85 per share. The NAV per share of our common stock at December 31, 2023 (the last date prior to the date of this prospectus on which we determined NAV per share) was $16.99.

Shares of closed-end investment companies, including BDCs, that are listed on an exchange frequently trade at a discount to their NAV per share. If our shares trade at a discount to our NAV per share, it may increase the risk of loss for purchasers in any offerings pursuant to this prospectus and any accompanying prospectus supplements.

This prospectus and any accompanying prospectus supplements and any related free writing prospectus, including the documents incorporated by reference herein or therein, contain important information you should know before investing in our securities. Please read this prospectus and any accompanying prospectus supplements and any related free writing prospectus, including the documents incorporated by reference herein or therein, before you invest and keep each for future reference. Information required to be included in a Statement of Additional Information may be found in this prospectus and an accompanying prospectus supplement, as applicable. We also file annual, quarterly and current reports, proxy statements and other information about us with the SEC. You may obtain this information or make stockholder inquiries by written or oral request and free of charge by contacting us by mail at our principal executive offices located at One Vanderbilt Avenue, Suite 3400, New York, NY 10017, on our website at http://carlylesecuredlending.com/, or by calling us at (212) 813-4900. Information contained on our website is not incorporated by reference into this prospectus, and you should not consider that information to be a part of this prospectus. The SEC also maintains a website at http://www.sec.gov that contains this information.

Investing in our securities involves a high degree of risk, including credit risk and the risk of the use of leverage, and is highly speculative. Before buying any securities, you should read the discussion of the material risks of investing in our securities that are described in the "Risk Factors" section beginning on page 14 of this prospectus and in the documents incorporated by reference herein, as well as in the applicable prospectus supplement and in any related free writing prospectus that we have authorized for use in connection with a specific offering, and under similar headings in other documents that are incorporated by reference into this prospectus.

We invest in securities that have been rated below investment grade by independent rating agencies or that would be rated below investment grade if they were rated. These securities, which are often referred to as "junk" or "high yield," have predominantly speculative characteristics with respect to the issuer's capacity to pay interest and repay principal. They may also be difficult to value and illiquid.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

This prospectus may not be used to consummate sales of securities unless accompanied by a prospectus supplement.

The date of this prospectus is April 29, 2024.

INDEX

You should rely only on the information contained or incorporated by reference in this prospectus, any accompanying prospectus supplements or any free writing prospectus prepared by us or on our behalf or to which we have referred you. We have not authorized any other person to provide you with different information or to make any representations not contained in this prospectus, any accompanying prospectus supplements or any free writing prospectus. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should not assume the information contained in this prospectus, any prospectus supplement or any free writing prospectus is accurate after their respective dates. Our business, financial condition, results of operations and prospects may have changed since that date.

TRADEMARKS

This prospectus contains trademarks and service marks owned by Carlyle (as defined below). This prospectus may also contain trademarks and service marks owned by third parties.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we have filed with the U.S. Securities and Exchange Commission, using the "shelf" registration process. Under the shelf registration process, which includes a delayed offering in reliance on Rule 415 under the Securities Act of 1933, as amended (the "Securities Act"), we may offer, from time to time, in one or more offerings or series, our common stock, preferred stock, debt securities, subscription rights to purchase shares of our common stock, warrants representing rights to purchase shares of our common stock, preferred stock or debt securities, or units comprised of any combination of the foregoing, on terms to be determined at the time of the offering.

The securities may be offered at prices and on terms described in one or more supplements to this prospectus. This prospectus provides you with a general description of the securities that we may offer. Each time we use this prospectus to offer securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. Please carefully read this prospectus and any accompanying prospectus supplements, including any information incorporated herein by reference, together with any exhibits and the additional information described under the headings "Additional Information" and "Risk Factors" and in the documents we have referred you to in "Information Incorporated by Reference" before you make an investment decision.

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RISK FACTORS

An investment in the Company involves a high degree of risk. You should carefully consider the risks set out below and described in Part I, Item 1A, "Risk Factors," in our 2023 Annual Report, which is incorporated herein by reference, together with the other information set forth in this prospectus and in the other documents that we include or incorporate by reference into this prospectus before making a decision about investing in our securities. Please refer to the section of our 2023 Annual Report entitled "Risk Factors - Risks Related to an Investment in Our Securities" which is incorporated by reference herein, for a discussion of the risks of investing in the Company.The risks set out below and discussed in our 2023 Annual Report are not the only risks we face. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition and/or operating results. The following considerations, together with all of the other information included in this prospectus and the accompanying prospectus supplement, including our consolidated financial statements and the related notes thereto, should be carefully evaluated before making an investment in the Company. If any of the following events occur, our business, financial condition and operating result could be materially and adversely affected. In such case, our NAV and the trading price of our common stock and the trading price, if any, of any other securities that we may issue could decline, and you may lose all or part of your investment.

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FORWARD-LOOKING STATEMENTS

This prospectus, including the documents that we incorporated by reference, contains forward-looking statements that involve substantial risks and uncertainties. You can identify these statements by the use of forward-looking terminology such as "anticipates," "believes," "expects," "intends," "will," "should," "may," "plans," "continue," "believes," "seeks," "estimates," "would," "could," "targets," "projects," "outlook," "potential," "predicts" and variations of these words and similar expressions to identify forward-looking statements, although not all forward-looking statements include these words. You should read statements that contain these words carefully because they discuss our plans, strategies, prospects and expectations concerning our business, operating results, financial condition and other similar matters. We believe that it is important to communicate our future expectations to our investors. Our forward-looking statements include information in this prospectus regarding general domestic and global economic conditions, our future financing plans, our ability to operate as a BDC and the expected performance of, and the yield on, our portfolio companies. In particular, there are forward-looking statements under "Summary- Carlyle Secured Lending, Inc." There may be events in the future, however, that we are not able to predict accurately or control. The factors listed under "Risk Factors," as well as any cautionary language in this prospectus and "Risk Factors," "Business," and "Management's Discussion and Analysis of Financial Condition and Results of Operations" of our 2023 Annual Report, and those discussed in other documents we file with the SEC and the documents incorporated by reference herein, provide examples of risks, uncertainties and events that may cause our actual results to differ materially from the expectations we describe in our forward-looking statements. Before you invest in our securities, you should be aware that the occurrence of the events described in these risk factors and elsewhere in this prospectus could have a material adverse effect on our business, results of operation and financial position. You should not place undue reliance on these forward-looking statements, which speak only as of the date on which we make it. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. We undertake no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law. Under Sections 27A(b)(2) of the Securities Act and Section 21E(b)(2) of the Exchange Act, the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995 do not apply to statements made in connection with any offering of securities pursuant to this prospectus or in a beneficial ownership report we file under the Exchange Act.

In addition to factors identified elsewhere in this prospectus and the documents incorporated by reference herein, the following factors are among those that may cause actual results to differ materially from our forward-looking statements:

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Our actual results and condition could differ materially from those implied or expressed in the forward-looking statements for any reason, including the factors set forth in "Risk Factors," elsewhere in this prospectus and in Part I, Item 1A of our 2023 Annual Report and in the other documents we file with the SEC.

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USE OF PROCEEDS

Unless otherwise specified in a prospectus supplement, we intend to use the net proceeds from the sale of our securities pursuant to this prospectus for general corporate purposes, which may include, among other things: (i) investing in portfolio companies in accordance with our investment objective and (ii) repaying or repurchasing outstanding indebtedness, which may include indebtedness under the Credit Facility, and, if specified in the prospectus supplement, we may use such net proceeds for acquisitions.

The supplement to this prospectus relating to an offering may more fully identify the use of the proceeds from such offering.

We anticipate that substantially all of the net proceeds of an offering of securities pursuant to this prospectus and its related prospectus supplement will be used for the above purposes within three months of any such offering, depending on the availability of appropriate investment opportunities consistent with our investment objective. We cannot assure you that we will achieve our targeted investment pace.

Proceeds not immediately used for new investments or the temporary repayment of debt will be invested primarily in cash, cash equivalents, U.S. government securities and other high quality short-term investments. These securities may earn lower yields than the types of investments we would typically make in accordance with our investment objective and, accordingly, may result in lower dividends, if any, during such period.

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PRICE RANGE OF COMMON STOCK AND DISTRIBUTIONS

Our common stock is traded on The Nasdaq Global Select Market under the symbol "CGBD." Our common stock has historically traded at prices both above and below our NAV per share. It is not possible to predict whether our common stock will trade at, above or below NAV. See "Risk Factors-Risks Related to Offerings Pursuant to this Prospectus-Our shares of common stock have traded at a discount from NAV and may do so again, which could limit our ability to raise additional equity capital."

The following table sets forth, for our two most recent fiscal years and our most recently completed fiscal quarter, the NAV per share of our common stock, the range of high and low closing sales prices of our common stock, the closing sales price as a premium (discount) to NAV and the dividends or distributions declared by us. On April 25, 2023, the last reported closing sales price of our common stock on The Nasdaq Global Select Market was $16.85 per share, which represented a discount of approximately 0.82% to the NAV per share reported by us as of December 31, 2023.

To the extent that we have taxable income available, we intend to distribute quarterly dividends to our stockholders. The amount of our dividends, if any, will be determined by our Board. Any dividends to our stockholders will be declared out of assets legally available for distribution. We anticipate that our distributions will generally be paid from taxable earnings, including interest and capital gains generated by our investment portfolio, and any other income, including any other fees (other than fees for providing managerial assistance), such as commitment, origination, structuring, diligence and consulting fees or other fees, that we receive from portfolio companies. However, if we do not generate sufficient taxable earnings during a year, all or part of a distribution may constitute a return of capital. The specific tax characteristics of our dividends and other distributions will be reported to stockholders after the end of each calendar year. See "U.S. Federal Income Tax Considerations" for further information regarding the tax treatment of our distributions and the tax consequences of our retention of net capital gains.

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The following table summarizes the Company's dividends declared during the two most recent fiscal years and the current fiscal year to date:

We have elected to be treated, and intend to continue to qualify annually, as a RIC. To maintain our qualification as a RIC, we must, among other things, fulfill the Annual Distribution Requirement, the 90% Gross Income Test and the Diversification Tests (each defined term, defined and more fully explained below in "U.S. Federal Income Tax Considerations-Taxation as a Regulated Investment Company"). In order to avoid certain excise taxes imposed on RICs, we intend to distribute during each calendar year an amount in accordance with the Excise Tax Distribution Requirements, as defined and discussed further below in "U.S. Federal Income Tax Considerations-Taxation as a Regulated Investment Company."

In addition, although we currently intend to distribute realized net capital gains (i.e., net long term capital gains in excess of short term capital losses), if any, at least annually, we may in the future decide to retain such capital gains for investment, pay U.S. federal income tax on such amounts at regular corporate tax rates, and elect to treat such gains as deemed distributions to stockholders. As a BDC, we are generally required to meet a minimum "asset coverage" ratio after each issuance of senior securities. "Asset coverage" generally refers to a

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company's total assets, less all liabilities and indebtedness not represented by "senior securities," as defined in the Investment Company Act, divided by total senior securities representing indebtedness and, if applicable, preferred stock. "Senior securities" for this purpose includes borrowings from banks or other lenders, debt securities and preferred stock. On April 9, 2018 and June 6, 2018, our Board, including a "required majority" (as such term is defined in Section 57(o) of the Investment Company Act), and our stockholders, respectively, approved the application to us of the 150% minimum asset coverage ratio set forth in Section 61(a)(2) of the Investment Company Act. As a result, the minimum asset coverage ratio applicable to us was reduced from 200% to 150%, effective as of June 7, 2018, the first day after our 2018 annual meeting of stockholders. As of December 31, 2023, our asset coverage calculated in accordance with the Investment Company Act was 183.4%. We can offer no assurance that we will achieve results that will permit the payment of any cash distributions and, to the extent that we issue senior securities, we will be prohibited from making distributions if doing so causes us to fail to maintain the asset coverage ratios stipulated by the Investment Company Act or if distributions are limited by the terms of any of our borrowings. See "Risk Factors-Risks Related to Offerings Pursuant to this Prospectus-If the current period of capital market disruption and instability continues for an extended period of time, there is a risk that our stockholders may not receive distributions or that our distributions may not grow over time and a portion of our distributions to you may be a return of capital for U.S. federal income tax purposes."

Unless you elect to receive your distributions in cash, we intend to make distributions in additional shares of our common stock under our dividend reinvestment plan. We generally intend to pay distributions in cash to stockholders who have "opted out" of our dividend reinvestment plan. However, we reserve the right, in our sole discretion from time to time, to limit the total amount of cash distributed to as little as 20% of the total distribution depending on, among other factors, the levels of our cash balances. See "Dividend Reinvestment Plan." We can offer no assurance that we will achieve results that will permit the payment of any cash distributions and, if we issue senior securities, we will be prohibited from making distributions if doing so causes us to fail to maintain the asset coverage ratios stipulated by the Investment Company Act or if distributions are limited by the terms of any of our borrowings.

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MANAGEMENT'S DISCUSSION AND ANALYSIS OF

FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The information in "Management's Discussion and Analysis of Financial Condition and Results of Operations" in Part II, Item 7 of our 2023 Annual Report is incorporated herein by reference.

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SENIOR SECURITIES

The information in "Senior Securities" in Note 11 to our consolidated financial statements in our 2023 Annual Report is incorporated herein by reference. This information about our senior securities should be read in conjunction with our audited consolidated financial statements and related notes thereto and the section titled "Management's Discussion and Analysis of Financial Condition and Results of Operations" included in our 2023 Annual Report, as well as any amendments reflected in subsequent filings with the SEC.

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BUSINESS

The information in "Business" in Part I, Item 1, "Properties" in Part I, Item 2 and "Legal Proceedings" in Part I, Item 3 of our 2023 Annual Report is incorporated herein by reference.

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PORTFOLIO COMPANIES

The table set forth below contains certain information as of December 31, 2023 for each portfolio company in which we had an investment. Other than these investments, our only formal relationships with our portfolio companies are the managerial assistance that we may provide upon request and any board observer or participation rights we may receive in connection with our investment. In general, under the Investment Company Act, we would be presumed to "control" a portfolio company if we owned more than 25% of its voting securities and would be an "affiliate" of a portfolio company if we owned more than 5% of its outstanding voting securities. As a result, for purposes of the Investment Company Act, we are an affiliate of, and are presumed to control, Credit Fund and Credit Fund II. For purposes of the Investment Company Act, as of December 31, 2023, we were also an affiliate of, but are not presumed to control, Direct Travel, Inc. We have exited our investment in Direct Travel, Inc. As of March 31, 2024, we are an affiliate of, but are not presumed to control Derm Growth Partners.

Each of our investments in Credit Fund and Credit Fund II represents greater than 5% of our total assets as of December 31, 2023. For additional information on Credit Fund, see "Middle Market Credit Fund, LLC" in Part II, Item 7 of our 2023 Annual Report and in Note 5 to our consolidated financial statements in our 2023 Annual Report, which are incorporated herein by reference. For additional information on Credit Fund II, see "Middle Markets Credit Fund II, LLC" in Part II, Item 7 of our 2023 Annual Report and in Note 6 to our consolidated financial statements in our 2023 Annual Report, which are incorporated herein by reference.

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