MetWest Low Duration Bond Fund

I SHARE: MWLIX  |  M SHARE: MWLDX  |  ADMIN SHARE: MWLNX

JULY 29

SUMMARY

PROSPECTUS

Before you invest, you may want to review the Fund’s Prospectus which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, Statement of Additional Information and other information about the Fund online at www.TCW.com. You can also get this information at no cost by calling 1-800-241-4671 or by sending an email request to metwestclientservices@tcw.com. The Fund’s current Prospectus and Statement of Additional Information, both dated July 29, 2021, are incorporated by reference into this Summary Prospectus. The Securities and Exchange Commission has not approved or disapproved these securities or passed on the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Paper copies of the Funds’ annual and semi-annual shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports. Instead, the reports will be made available on the Funds’ website (www.TCW.com), and you will be notified by mail each time a report is posted and provided with a website link to access the report. You may elect to receive all future reports in paper free of charge. Contact your financial intermediary or, if you invest directly with the Funds, call (800) 241-4671 to request that you continue receiving paper copies of your shareholder reports. Your election to receive reports in paper will apply to all Funds held through your financial intermediary or directly with TCW.

MW-LD_0721

Investment Objective

The Low Duration Bond Fund seeks to maximize current income, consistent with preservation of capital.

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.

Shareholder Fees (Fees paid directly from your investment)

None.

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

	M Class		I Class		Administrative Class
Management Fees		0.30%		0.30%		0.30%
Distribution (12b-1) Fees		0.19%		None		0.19%
Other Expenses		0.13%		0.12%		0.24%
Shareholder Servicing Expenses1		0.09%		0.08%		0.20%
Total Annual Fund Operating Expenses		0.62%		0.42%		0.73%

¹   For the Administrative Class Shares, includes up to 0.20% charged under the Shareholder Servicing Plan. The Fund is authorized to compensate broker-dealers and other third-party intermediaries up to 0.10% (10 basis points) of the M and I Class assets serviced by those intermediaries for shareholder services.

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:

	1 Year			3 Years			5 Years			10 Years
Class M		$	63		$	199		$	346		$	774
Class I		$	43		$	135		$	235		$	530
Administrative Class		$	75		$	233		$	406		$	906

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 256% of the average value of its portfolio.

Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 70% of its net assets in highly rated fixed income securities or unrated securities determined by the Adviser to be of comparable quality. Up to 30% of the Fund’s net assets may be invested in securities rated below highly rated securities or unrated securities determined by the Adviser to be of comparable quality, but not more than 20% of the Fund’s net assets may be invested in securities rated below investment grade (commonly known as “junk bonds”) or unrated securities determined by the Adviser to be of comparable quality. The Fund also invests, under normal circumstances, at least 80% of its net assets, plus any borrowings for investment purposes, in fixed income securities it regards as bonds. 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. Under normal circumstances, the Fund’s portfolio duration is up to three years and the Fund’s dollar-weighted average maturity ranges from one to five 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.

The Fund invests in the U.S. and abroad, including emerging markets, and may purchase securities of varying maturities issued by domestic and foreign corporations and governments.

The Fund may invest up to 25% of its assets in foreign securities that are denominated in U.S. dollars. The Fund may

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invest up to 15% of its assets in securities of foreign issuers that are not denominated in U.S. dollars. The Fund may invest up to 10% of its assets in emerging market securities.

The Fund’s investments include various types of bonds and debt securities, including corporate bonds, notes, mortgage-related and asset-backed securities (including collateralized debt obligations, which in turn include collateralized bond obligations and collateralized loan obligations), bank loans, U.S. and non-U.S. money market securities, swaps (including credit default swaps), futures, options (including swaptions), municipal securities, defaulted debt securities, private placements and restricted securities. The Fund’s fixed income investments may have interest rates that are fixed, variable or floating.

Derivatives are used in an effort to hedge investments, for risk management, or to increase income or gains for the Fund. The Fund may also seek to obtain market exposure to the securities in which it invests by entering into a series of purchase and sale contracts or by using other investment techniques such as reverse repurchase agreements. The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.

The Fund may normally short sell up to 25% of the value of its total assets.

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:

• Debt Securities Risk: the risk that the value of a debt security may increase or decrease as a result of various factors, including changes in interest rates, actual or perceived inability or unwillingness of issuers to make principal or interest payments, market fluctuations and illiquidity in the debt securities market.

• Market Risk: the risk that returns from the securities in which the Fund invests may underperform returns from the general securities markets or other types of securities.

• Interest Rate Risk: the risk that debt securities may decline in value because of changes in interest rates.

• Credit Risk: the risk that an issuer may default in the payment of principal and/or interest on a security.

• Price Volatility Risk: the risk that the value of the Fund’s investment portfolio will change as the prices of its investments go up or down.

• Issuer Risk: the risk that the value of a security may decline for reasons directly related to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods or services.

• Liquidity Risk: the risk that lack of a ready market or restrictions on resale may limit the ability of the Fund to sell a security at an advantageous time or price. In addition, the Fund, by itself or together with other accounts managed by the Adviser, may hold a position in a security that is large relative to the typical trading volume for that security, which can make it difficult for the Fund to dispose of the position at an advantageous time or price. Over recent years, the fixed-income markets have grown more than the ability of dealers to make markets, which can further constrain liquidity and increase the volatility of portfolio valuations. High levels of redemptions in bond funds in response to market conditions could cause greater losses as a result. Regulations such as the Volcker Rule or future regulations may further constrain the ability of market participants to create liquidity, particularly in times of increased market volatility. The liquidity of the Fund’s assets may change over time.

• Frequent Trading Risk: the risk that frequent trading may lead to increased portfolio turnover and higher transaction costs, which may reduce the Fund’s performance and may cause higher levels of current tax liability to shareholders of the Fund.

• Valuation Risk: the risk that the portfolio instruments may be sold at prices different from the values established by the Fund, particularly for investments that trade in low volume, in volatile markets or over the counter or that are fair valued.

• Prepayment Risk: the risk that in times of declining interest rates, the Fund’s higher yielding securities may be prepaid and the Fund may have to replace them with securities having a lower yield.

• Extension Risk: the risk that in times of rising interest rates, borrowers may pay off their debt obligations more slowly, causing securities considered short- or intermediate-term to become longer-term securities that fluctuate more widely in response to changes in interest rates than shorter-term securities.

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• Mortgage-Backed Securities Risk: the risk of investing in mortgage-backed securities, including prepayment risk and extension risk. Mortgage-backed securities react differently to changes in interests rates than other bonds, and some mortgage-backed securities are not backed by the full faith and credit of the U.S. government.

• Asset-Backed Securities Risk: the risk of investing in asset-backed securities, including the risk of loss as a result of the impairment of the value of the underlying financial assets, prepayment risk and extension risk. Issuers of asset-backed securities may have limited ability to enforce the security interest in the underlying assets, and credit enhancements provided to support the asset-backed securities, if any, may be inadequate to protect investors in the event of default.

• U.S. Treasury Obligations Risk: the risk that the value of U.S. treasury obligations may decline as a result of changes in interest rates, certain political events in the U.S., and strained relations with certain foreign countries.

• U.S. Government Securities Risk: the risk that debt securities issued or guaranteed by certain U.S. government agencies, instrumentalities, and sponsored enterprises are not supported by the full faith and credit of the U.S. government, and as a result, investments in securities or obligations issued by such entities involve credit risk greater than investments in other types of U.S. government securities.

• Derivatives Risk: the risk of investing in derivative instruments, which includes liquidity, interest rate, market, credit and management risks as well as risks related to mispricing or improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, reference rate or index, and the Fund could lose more than the principal amount invested. These investments can create investment leverage and may create additional risks that may subject the Fund to greater volatility and less liquidity than investments in more traditional securities.

• Leverage Risk: the risk that leverage may result from certain transactions, including the use of derivatives and borrowing. This may impair the Fund’s liquidity, cause it to liquidate positions at an unfavorable time, increase its volatility or otherwise cause it not to achieve its intended result. To the extent required by applicable law or regulation, the Fund will reduce leverage risk by either segregating an equal amount of liquid assets or “covering” the transactions that introduce such risk.

• Counterparty Risk: the risk that the other party to a contract, such as a derivatives contract, may not fulfill its contractual obligations.

• Futures Contracts Risk: the risk of investing in futures contracts, which includes (1) the imperfect correlation between a futures contract and the change in market value of the underlying instrument held by the Fund; (2) a high degree of leverage because of the low collateral deposits normally involved in futures trading; (3) possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (4) losses caused by unanticipated market movements, which are potentially unlimited; and (5) the inability of the Fund to execute a trade because of the maximum permissible price movements exchanges may impose on futures contracts.

• Swap Agreements Risk: the risk of investing in swaps, which, in addition to risks applicable to derivatives generally, includes: (1) the inability to assign a swap contract without the consent of the counterparty; (2) potential default of the counterparty to a swap for those not traded through a central counterparty; (3) absence of a liquid secondary market for any particular swap at any time; and (4) possible inability of the Fund to close out a swap transaction at a time that otherwise would be favorable for it to do so.

• Junk Bond Risk: the risk that junk bonds have a higher degree of default risk and may be less liquid and subject to greater price volatility than investment grade bonds.

• Unrated Securities Risk: the risk that unrated securities may be less liquid than comparable rated securities, and the risk that the Adviser may not accurately evaluate the security’s comparative credit rating.

• Short Sales Risk: the risk that the use of short sales, which are speculative investments, may cause the Fund to lose money if the value of a security does not go down as the Adviser expects. The risk of loss is theoretically unlimited if the value of the security sold short continues to increase. In addition, the use of borrowing and short sales may cause the Fund to have higher expenses (especially interest and dividend expenses) than those of other mutual funds that do not engage in short sales.

• Foreign Investing Risk: the risk that Fund share prices will fluctuate with market conditions, currency exchange rates and the economic and political climates of the foreign countries in which the Fund invests or has exposure. Investments in foreign securities may involve greater risks than investing in U.S. securities due to, among other factors, less publicly available information, less stringent and less uniform accounting, auditing and financial reporting standards, less liquid and more volatile markets, higher transaction and custody costs, additional taxes, less investor protection, delayed or less frequent settlement,

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political or social instability, civil unrest, acts of terrorism, regional economic volatility, and the imposition of sanctions, confiscations, trade restrictions (including tariffs) and other government restrictions by the United States and/or other governments.

• Foreign Currency Risk: the risk that foreign currencies may decline in value relative to the U.S. dollar and affect the Fund’s investments in foreign currencies, in securities that are denominated, trade and/or receive revenues in foreign currencies, or in derivatives that provide exposure to foreign currencies.

• Emerging Markets Risk: the risk of investing in emerging market countries, which is substantial due to, among other factors, higher brokerage costs in certain countries; different accounting standards; thinner trading markets as compared to those in developed countries; less publicly available and reliable information about issuers as compared to developed markets; the possibility of currency transfer restrictions; and the risk of expropriation, nationalization or other adverse political, economic or social developments.

• Distressed and Defaulted Securities Risk: the risk that the repayment of defaulted securities and obligations of distressed issuers is subject to significant uncertainties.

• Securities Selection Risk: the risk that the securities held by the Fund may underperform those held by other funds investing in the same asset class or those included in benchmarks that are representative of the same asset class because of the portfolio managers’ choice of securities.

• Portfolio Management Risk: the risk that an investment strategy may fail to produce the intended results.

• Public Health Emergency Risk: the risk that pandemics and other public health emergencies, including outbreaks of infectious diseases such as the current outbreak of the novel coronavirus (“COVID-19”), can result, and in the case of COVID-19 is resulting, in market volatility and disruption, and materially and adversely impact economic conditions in ways that cannot be predicted, all of which could result in substantial investment losses. The ultimate impact of COVID-19 or other health emergencies on global economic conditions and businesses is impossible to predict accurately. Ongoing and potential additional material adverse economic effects of indeterminate duration and severity are possible. The resulting adverse impact on the value of an investment in the Fund could be significant and prolonged. Other public health emergencies that may arise in the future could have similar or other unforeseen effects.

• LIBOR Risk: the risk associated with the transition away from LIBOR, which is used extensively in the U.S. and globally as a “benchmark” or “reference rate” for various commercial and financial contracts, including corporate bonds and other fixed income securities. The use of LIBOR is anticipated to begin being phased out by the end of 2021. There remains uncertainty regarding the future utilization of LIBOR and the nature of any replacement rate, and the transition from and ultimate abandonment of or modifications to LIBOR could have adverse impacts on newly issued financial instruments and existing financial instruments that reference LIBOR, including those in which the Fund invests.

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 the performance of the Fund’s Class M Shares. Class M performance is lower than Class I performance and higher than Administrative Class performance because Class M has higher expenses than Class I and lower expenses than Administrative Class. The table compares the average annual total returns of the Fund to a broad-based securities market index. Total returns would have been lower if certain fees and expenses had not been waived or reimbursed. The inception dates of Class M shares, Class I shares and Administrative Class shares of the Fund are March 31, 1997, March 31, 2000 and September 23, 2009, respectively. 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.

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Low Duration Bond Fund – Class M Shares

Annual Total Returns for Years Ended 12/31

Year-to-Date Total Return of Class M Shares as of June 30, 2021: 0.14%

Highest:	2.98%	(quarter ended September 30, 2012)
Lowest:	-1.34%	(quarter ended September 30, 2011)

Average Annual Total Returns

(For Periods Ended December 31, 2020)

Share Class	1 Year		5 Years		10 Years		Since Inception
M – Before Taxes		3.27%		2.21%		2.31%		3.60%
- After Taxes on Distributions		2.68%		1.48%		1.53%		2.04%
- After Taxes on Distributions and Sale of Fund Shares		1.93%		1.37%		1.45%		2.12%
I – Before Taxes		3.49%		2.42%		2.50%		3.30%
Administrative – Before Taxes		3.28%		2.11%		2.16%		3.22%
BofA Merrill Lynch 1-3 Year U.S. Treasury Index		3.10%		1.90%		1.30%		3.19%

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

Name	Experience with the Fund	Primary Title with Investment Adviser
Tad Rivelle	25 Years	Founding Partner, Chief Investment Officer and Generalist Portfolio Manager
Stephen M. Kane, CFA	25 Years	Founding Partner and Generalist Portfolio Manager
Laird Landmann	25 Years	Founding Partner and Generalist Portfolio Manager
Bryan T. Whalen, CFA	17 Years	Generalist Portfolio Manager

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 (Metropolitan West Funds, c/o BNY Mellon Investment Servicing, P.O. Box 9793, Providence, RI 02940), or by telephone at (800) 241-4671. You may also purchase or redeem shares of the Funds through your dealer or financial advisor. Plan Class shares offered by the Total Return Bond Fund are intended for retirement plans, including defined benefit and defined contribution plans (which may include participant-directed plans).

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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.

Share Class and Type of Account	Minimum Initial Investment		Minimum Subsequent Investment
Class M
Regular Accounts	$	5,000	$	0
Individual Retirement Accounts	$	1,000	$	0
Automatic Investment Plan	$	5,000	$	100
Class I
Regular Accounts	$	3,000,000	$	50,000
Administrative Class
Regular Accounts	$	2,500	$	0
Individual Retirement Accounts	$	1,000	$	0

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.

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