Summary Prospectus by Investment Company - Form 497K

Investment Objective

The Unconstrained Bond Fund seeks to provide investors with positive long-term returns irrespective of general securities market conditions.

Fees and Expenses of the Fund

The table below describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A

higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 257% of the average value of its portfolio.

Principal Investment Strategies

The Fund pursues its objective by utilizing a flexible investment approach that allocates investments across a range of global investment opportunities related to credit, currencies and interest rates. Satisfying the Fund's objective would require it to achieve positive total returns over a full market cycle, i.e., a period of time generally understood to be contained between two consecutive periods of heightened default activity within the global fixed income markets. Total return includes income and capital gains.

The use of the term "unconstrained" in the Fund's name means that it is not limited by the types of investments in a particular securities index. The Fund is not managed to be compared to any such index. The Fund also is unconstrained in the sense that it is not limited to any single type of investment strategy.

The portfolio management team evaluates each investment idea based on the team's view of, among other factors, its potential return, its risk level and how it fits within the Fund's overall portfolio in determining whether to buy or sell investments. The Adviser allocates the Fund's assets in response to, among other considerations, changing market, financial, economic, and political factors and events that the Fund's portfolio managers believe may affect the values of the Fund's investments. The allocation of capital to sectors and securities within each sector in the Fund is driven primarily by the Adviser's assessment of relative value offered by each sector and security, respectively.

The Adviser seeks to actively manage the Fund's risks on an on-going basis to mitigate the risks of excessive losses by the portfolio overall. In managing portfolio risk, the Adviser takes into consideration its view of the following factors, among others: the potential relative performance of various market sectors, security selection available within a given sector, the risk/reward equation for different asset classes, liquidity conditions in various market sectors, the shape of the yield curve and projections for changes in the yield curve, potential fluctuations in the overall level of interest rates, and current monetary and fiscal policy.

The Fund invests, under normal circumstances, at least 80% of its net assets, plus any borrowings for investment purposes, in securities and instruments it regards as bonds in the U.S. and abroad, including emerging markets, and may purchase securities of varying maturities issued by domestic and foreign corporations and governments. A bond is a security or instrument having one or more of the following characteristics: a fixed-income security, a security issued at a discount to its face value, a security that pays interest or a security with a stated principal amount that requires repayment of some or all of that principal amount to the holder of the security. The term "bond" is interpreted broadly by the Adviser as an instrument or security evidencing a promise to pay some amount rather than evidencing the corporate ownership of equity, unless that equity represents an indirect or derivative interest in one or more bonds. The Fund may invest in both investment grade and high yield fixed income securities (commonly known as "junk bonds"), subject to investing no more than 50% of its total assets (measured at the time of investment) in securities rated below investment grade by Moody's, S&P or Fitch, or, if unrated, determined by the Adviser to be of comparable quality. Under normal circumstances, the average portfolio duration of the fixed-income portion of the Fund's portfolio will vary from negative three (-3) years to positive eight (8) years. Duration is a measure of the expected life of a fixed income security that is used to determine the sensitivity of a security to changes in interest rates. As a separate measure, there is no limit on the weighted average maturity of the Fund's portfolio.

The Fund may invest in foreign securities, and up to 50% of the Fund's total assets may be invested in emerging markets and instruments that are economically tied to emerging market countries. The Fund considers emerging market countries to include all of the countries in the J.P. Morgan Emerging Market Bond Index (EMBI) Global Diversified, the J.P. Morgan Corporate Emerging Market Bond Index (CEMBI) Broad Diversified, the J.P. Morgan Government Bond Index-Emerging Markets (GBI-EM), the MSCI Emerging Markets Index and the MSCI Frontier Markets Index. Instruments considered to be economically tied to emerging market countries are (i) those that are principally traded in an emerging market country, or (ii) those that are issued by: (a) an issuer organized under the laws of or maintaining a principal place of business in an emerging market country, (b) an issuer that derives or is expected to derive 50% or more of its total revenues, earnings or profits from business activity in an emerging market country, or that maintains or is expected to maintain 50% or more of its employees, assets, investments or operations in an emerging market country, or (c) a gov-

ernmental or quasi-governmental entity of an emerging market country. The emerging market fixed-income securities in which the Fund may invest are not subject to any minimum credit quality standards, so long as the value of those investments does not cause the Fund to exceed its limit on investments in securities rated below investment grade.

The Fund normally limits its foreign currency exposure (from non-U.S. dollar-denominated securities or currencies) to 40% of its total assets. The Fund reserves the right to hedge its exposure to foreign currencies to reduce the risk of loss from fluctuations in currency exchange rates, but is under no obligation to do so under any circumstances.

The Fund may sell securities and other instruments short provided that not more than 25% of its net assets is held as collateral for those transactions. Derivatives are used in an effort to hedge investments, for risk management or to increase income or gains for the Fund. The types of derivative instruments in which the Fund will principally invest are currency and other futures, forward contracts, options, and swap agreements (typically interest rate swaps, index-linked swaps, total return swaps and credit default swaps). The Fund may invest up to 10% of its total assets in preferred stock and up to 5% in common stock of domestic and foreign companies. The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.

Principal Risks

Because the Fund holds securities with fluctuating market prices, the value of the Fund's shares will vary as its portfolio securities increase or decrease in value. Therefore, the value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund.

The principal risks affecting the Fund that can cause a decline in value are:

Please see "Principal Risks" and "Other Risks" for a more detailed description of the risks of investing in the Fund.

Your investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, entity, or person.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund's performance from year to year. The bar chart shows performance of the Fund's Class M shares. Class M performance is lower than Class I performance because Class I has lower expenses than Class M. The table compares the average annual total returns of the Fund to a broad-based securities market index and a secondary benchmark index. Total returns would have been lower if certain fees and expenses had not been waived or reimbursed. The inception date of Class M shares and Class I shares of the Fund is September 30, 2011. The inception date for the Plan Class shares is March 6, 2020. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance information for the Fund is available on our website at www.tcw.com or by calling (800) 241-4671.

Unconstrained Bond Fund - Class M Shares

Annual Total Returns for Year Ended 12/31

Year-to-Date Total Return of Class M Shares as of June 30, 2024: 2.00%

Average Annual Total Returns

(For Periods Ended December 31, 2023)

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for only Class M Shares. After-tax returns for other classes will vary. In some cases, returns after taxes on distributions and sale of Fund shares may be higher than returns before taxes because the calculations assume that the investor received a tax deduction for any loss incurred on the sale of the shares.

Investment Adviser

Metropolitan West Asset Management, LLC.

Portfolio Managers

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Funds on any business day (normally any day that the New York Stock Exchange is open). Generally, purchase and redemption orders for shares of the Funds are processed at the net asset value next calculated after an order is received by the Fund. You may conduct transactions by mail (TCW Metropolitan West Funds, c/o BNY Mellon Investment Servicing, P.O. Box 534453, Pittsburgh, PA 15253-4453), or by telephone at (800) 241-4671. You may also purchase or redeem shares of the Funds through your dealer or financial advisor.

Purchase Minimums for Each Share Class

The following table provides the minimum initial and subsequent investment requirements for each share class. The minimums may be reduced or waived in some cases. A broker-dealer or other financial intermediary may require a higher minimum initial investment, or may aggregate or combine accounts in order to allow its customers to apply a lower minimum investment. Participants in a defined contribution plan, such as a 401(k) plan, can invest in the Plan

Class only if the plan as a whole meets the minimum investment threshold.

Tax Information

Dividends and capital gains distributions you receive from the Fund are subject to federal income taxes and may also be subject to state and local taxes, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account. Such tax-deferred arrangements may be taxed later upon withdrawal from those arrangements.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and/or the Adviser may, directly or through the Fund's principal underwriter, pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information. Plan Class shares do not make payments to broker-dealers or other financial intermediaries.