PIMCO RAFI Dynamic Multi-Factor US Equity ETF

PIMCO RAFI Dynamic Multi-Factor U.S. Equity ETF

Summary Prospectus

October 31, 2025 (as supplemented August 18, 2026)

Ticker

MFUS

NYSE Arca

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, reports to shareholders and other information about the Fund online at http://investments.pimco.com/prospectuses. You can also get this information at no cost by calling 888.400.4ETF (888.400.4383) or by sending an email request to pimcoregdocgroup@pimco.com. The Fund’s prospectus and Statement of Additional Information, both dated October 31, 2025, as supplemented, are incorporated by reference into this Summary Prospectus.

Investment Objective

The Fund seeks to track the investment results of the RAFI Dynamic Multi-Factor U.S. Index.

Fees and Expenses of the Fund

This table 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):

N/A

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

Management Fees	0.29%
Other Expenses(1)	0.01%
Total Annual Fund Operating Expenses	0.30%
Fee Waiver and/or Expense Reimbursement(2)	(0.01%)
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	0.29%

“Other Expenses” include expenses incurred by the Fund in the normal course of its operations together with recoupment of management fees previously waived or reimbursed to the Fund. Such expenses are borne by the Fund separately from the management fees paid to Pacific Investment Management Company LLC (“PIMCO”).

PIMCO has contractually agreed, through October 31, 2026, to waive a portion of the Fund’s management fees, or reimburse the Fund, to the extent that the Fund’s organizational expenses, pro rata share of expenses related to obtaining or maintaining a Legal Entity Identifier and pro rata share of Trustee fees exceed 0.0049% (the “Expense Limit”) (calculated as a percentage of average daily net assets). This Expense Limitation Agreement will automatically renew for one-year terms unless PIMCO provides written notice to PIMCO Equity Series at least 30 days prior to the end of the then current term. In any month in which the investment management agreement is in effect, PIMCO is entitled to reimbursement by the Fund of any portion of the management fee waived or reimbursed as set forth above (the “Reimbursement Amount”) within thirty-six months of the time of the waiver, provided that such amount paid to PIMCO will not: 1) together with any organizational expenses, pro rata share of expenses related to obtaining or maintaining a Legal Entity Identifier and pro rata Trustee fees, exceed, for such month, the Expense Limit (or the amount of the expense limit in place at the time the amount being recouped was originally waived if lower than the Expense Limit); 2) exceed the total Reimbursement Amount; or 3) include any amounts previously reimbursed to PIMCO.

Example.

The Example is intended to help you compare the cost of investing in the Fund with the costs of investing in other exchange-traded funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated, and then hold or sell 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
$30	$95	$168	$380

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 the Annual Fund Operating Expenses or in the Example tables, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 40% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its total assets (exclusive of collateral held from securities lending) in the component securities (“Component Securities”) of the RAFI Dynamic Multi-Factor U.S. Index (the “Underlying Index”). The Fund may invest the remainder of its assets in cash, securities and instruments that are not Component Securities, but which PIMCO believes will help the Fund track its Underlying Index. The Underlying Index is designed to provide long-only exposure to multiple equity factors that seek to produce attractive long-term returns, and which may lower risk compared to less diversified strategies.

The Underlying Index is constructed by RAFI Indices, LLC (the “Index Provider”) using a rules-based approach to construct factor portfolios within the Underlying Index. The universe for the Underlying Index construction process starts with all common equity securities traded on primary exchanges, which meet and pass minimum liquidity and investability (capacity) requirements, issued by companies that are assigned to the United States by the Index Provider. The Index Provider assigns companies to countries and promulgates that assignment to securities. Eligible securities are then determined by selecting companies based on fundamental weight, calculated using four accounting measures from company financial statements: (i) de-levered sales, calculated as company sales averaged over the past five years multiplied by the ratio of average equity to average assets; (ii) cash flow, taken as the company operating cash flow averaged over the past five years; (iii) dividend plus buybacks, calculated using the average dividends paid and share buybacks over the past five years; and (iv) book value, taken as the most recent company book value. At each annual reconstitution, companies that rank in the top 86% of cumulative fundamental weight

PIMCO Equity Series | Summary Prospectus

PIMCO RAFI Dynamic Multi-Factor U.S. Equity ETF

within each region constitute the large/mid company universe. Companies that rank in the top 98% by fundamental weight, excluding companies in the top 86%, within each region constitute the small company universe.

The Underlying Index consists of “factor portfolios,” each of which emphasizes one of the following factors: value, low volatility, quality, momentum and size. The value factor emphasizes companies with a high ratio of company fundamental weight to its market capitalization weight. The low volatility factor emphasizes companies with low risk measure calculated as the variance of a company’s daily excess return over five years explained by global, local country groups, and global industry excess returns. The quality factor emphasizes companies that are high in profitability and low in investment spending. The momentum factor emphasizes stocks with high momentum. For the value, low volatility and quality “factor portfolios”, eligible securities are ranked by their factor score and the top 25% of companies by fundamental weight are selected for inclusion within that “factor portfolio”. For the momentum “factor portfolio”, eligible securities are ranked by their momentum score and the top 50% of companies by fundamental weight are selected for inclusion. The size factor is the equal weight of the small company portions of the other four factors. A company’s fundamental weight may be adjusted by a “free float factor”, which is the ratio of the total market capitalization of the shares of the company in free float to the total market capitalization of the company. As of September 30, 2025, the Underlying Index consisted of 831 Component Securities.

The Underlying Index dynamically allocates to each factor at each quarterly rebalance. Dynamic allocation starts with an equal weighting to each factor plus an additional weight, which is based on a calculation of a factor’s standard momentum and long-term reversal signal relative to the other factors. Additional weights to a particular factor are capped at a maximum of 15% and minimum of -15% relative to equal weighting.

Each factor (other than momentum) is reconstituted annually on the last Friday of March and rebalanced on a quarterly staggered basis on the last Friday of March, June, September and third Friday of December. For example, a single factor will be divided into four identical tranches. At the first quarterly rebalance, the first tranche (i.e., 25% of the factor) is rebalanced, but the remaining three tranches (i.e., the other 75% of the factor) are not rebalanced and will continue to drift until the next quarterly rebalance. At the next quarterly rebalance, the second tranche is rebalanced while the other three tranches (including the tranche that was rebalanced at the prior quarter-end) are not rebalanced. This staggered rebalancing is intended to diversify risk and decrease market impact. The momentum factor, unlike the other factors, is reconstituted and fully rebalanced quarterly. At each quarterly rebalance, trading controls are implemented to minimize turnover.

PIMCO uses an indexing approach in managing the Fund’s investments. The Fund is expected to employ a replication strategy in seeking to achieve its investment objective. In using this strategy, PIMCO seeks to replicate the composition and weighting of the Underlying Index by investing all, or substantially all, of the Fund’s assets in the Component

Securities, holding each Component Security in approximately the same proportion as its weighting in the Underlying Index. However, in some circumstances it may not be possible or practicable to invest all, or substantially all, of the Fund’s assets in the Component Securities, in which case the Fund may employ a representative sampling strategy by investing in a combination of Component Securities and other instruments, or in Component Securities but in different proportions as compared to the weighting of the Underlying Index, such that the portfolio effectively provides exposure to the Underlying Index. In using a representative sampling strategy, the Fund may not track its Underlying Index with the same degree of accuracy as a fund that replicates the composition and weighting of the Underlying Index. Unlike many investment companies, the Fund does not attempt to outperform the index the Fund tracks. An indexing approach may eliminate the chance that the Fund will substantially outperform its Underlying Index but also may reduce some of the risks of active management. Indexing seeks to achieve lower costs by keeping portfolio turnover low in comparison to actively managed investment companies.

The Fund may invest, without limitation, in equity and equity-related securities, including common and preferred securities. The Fund may also invest in derivative instruments, such as options, futures contracts or swap agreements.

Principal Risks

It is possible to lose money on an investment in the Fund. The principal risks of investing in the Fund, which could adversely affect its net asset value, yield and total return, are listed below.

Market Trading Risk: the risk that an active secondary trading market for Fund shares does not continue once developed, that the Fund may not continue to meet a listing exchange’s trading or listing requirements, that trading in Fund shares may be halted or become less liquid or that Fund shares trade at prices other than the Fund’s net asset value, and are subject to trading costs. These risks may be exacerbated if the creation/redemption process becomes less effective, particularly during times of market stress or volatility

Equity Risk: the risk that the value of equity or equity-related securities, such as common stocks and preferred securities, may decline due to general market conditions which are not specifically related to a particular company or to factors affecting a particular industry or industries. Equity or equity-related securities generally have greater price volatility than fixed income securities. In addition, preferred securities may be subject to greater credit risk or other risks, such as risks related to deferred and omitted distributions, limited voting rights, liquidity, interest rates, regulatory changes and special redemption rights

Credit Risk: the risk that the Fund could experience losses if the counterparty to a derivative contract, or the issuer or guarantor of collateral, is unable or unwilling, or is perceived (whether by market participants, rating agencies, pricing services or otherwise) as unable or unwilling, to meet its financial obligations

2 Summary Prospectus | PIMCO Equity Series

Summary Prospectus

Market Risk: the risk that the value of securities owned by the Fund may fluctuate, sometimes rapidly or unpredictably, due to a variety of factors affecting securities markets generally or particular industries or sectors

Liquidity Risk: the risk that a particular investment may be difficult to purchase or sell and that the Fund may be unable to sell investments at an advantageous time or price or achieve its desired level of exposure to a certain sector. The liquidity of the Fund’s shares may be constrained by the liquidity of the Fund’s portfolio holdings

Issuer Risk: the risk that the value of a security may decline for reasons related to the issuer, such as management performance, changes in financial condition or credit rating, financial leverage, reputation or reduced demand for the issuer’s goods or services

Derivatives Risk: the risk of investing in derivative instruments (such as forwards, futures, options, swaps and structured securities) and other similar investments, including leverage, liquidity, interest rate, market, counterparty (including credit), operational, legal and management risks and valuation complexity. Changes in the value of a derivative or other similar investment may not correlate perfectly with, and may be more sensitive to market events than, the underlying asset, rate or index, and the Fund could lose more than the initial amount invested. Changes in the value of a derivative or other similar instrument may also create margin delivery or settlement payment obligations for the Fund. The Fund’s use of derivatives or other similar investments may result in losses to the Fund, a reduction in the Fund’s returns and/or increased volatility. Non-centrally-cleared over-the-counter (“OTC”) derivatives or other similar investments are also subject to the risk that a counterparty to the transaction will not fulfill its contractual obligations to the other party, as many of the protections afforded to centrally-cleared derivative transactions might not be available for non-centrally-cleared OTC derivatives or other similar investments. The primary credit risk on derivatives or other similar investments that are exchange-traded or traded through a central clearing counterparty resides with the Fund's clearing broker, or the clearinghouse. Changes in regulations relating to a registered fund’s use of derivatives and related instruments could potentially limit or impact the Fund’s ability to invest in derivatives, limit the Fund’s ability to employ certain strategies that use derivatives or other similar investments and/or adversely affect the value of derivatives or other similar investments and the Fund’s performance

Model Risk: the risk that the Fund’s investment models used in making investment allocation decisions, including the indexation methodologies used in constructing the Underlying Index, may not adequately take into account certain factors, may contain design flaws or faulty assumptions, and may rely on incomplete or inaccurate data inputs, any of which may result in a decline in the value of an investment in the Fund. The performance of the investment models may be impacted by software or other technology malfunctions, human error, programming inaccuracies, power loss, and other events or circumstances, which may be difficult to detect and may be beyond the control of the Fund

Leveraging Risk: the risk that certain transactions of the Fund, such as reverse repurchase agreements, loans of portfolio securities, and the use of when-issued, delayed delivery or forward commitment transactions, and derivative instruments, may give rise to leverage, magnifying gains and losses and causing the Fund to be more volatile than if it had not been leveraged. This means that leverage entails a heightened risk of loss. The use of leverage may also increase the Fund’s sensitivity to interest rate changes and other market risks

Management and Tracking Error Risk: the risk that a portfolio manager’s investment decisions may not produce the desired results or that the Fund’s portfolio may not closely track the Underlying Index for a number of reasons. The Fund incurs operating expenses, which are not applicable to the Underlying Index, and the transaction costs of buying and selling securities, especially when rebalancing the Fund’s portfolio to reflect changes in the composition of the Underlying Index. Performance of the Fund and the Underlying Index may vary due to asset valuation differences and differences between the Fund’s portfolio and the Underlying Index due to legal restrictions, cost or liquidity restraints. The risk that performance of the Fund and the Underlying Index may vary may be heightened during periods of increased market volatility or other unusual market conditions. In addition, to the extent the Fund uses a representative sampling approach, this approach may cause the Fund to be less correlated to the return of the Underlying Index than if the Fund held all of the securities in the Underlying Index

Indexing Risk: the risk that the Fund is negatively affected by general declines in the asset classes represented by the Underlying Index

Please see “Description of Principal Risks” in the Fund's prospectus for a more detailed description of the risks of investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance Information

The performance information shows summary performance information for the Fund in a bar chart and an Average Annual Total Returns table. The information provides some indication of the risks of investing in the Fund by showing changes in its performance from year to year and by showing how the Fund’s average annual returns compare with the returns of certain indexes. Absent any applicable fee waivers and/or expense limitations, performance would have been lower. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

In addition to the Fund’s performance, the Average Annual Total Returns table includes performance of: (i) a broad-based securities market index (i.e., a regulatory index) and (ii) a supplemental index. It is not possible to invest directly in an unmanaged index. The Fund’s regulatory index is the S&P 500 Index. The Fund’s regulatory index is shown in connection with certain regulatory requirements to provide a broad measure of market performance. The S&P 500 Index is an unmanaged market index generally considered representative of the stock market as a whole. The S&P 500 Index is composed of 500 selected common stocks that represent approximately two-thirds of the total market value of all

October 31, 2025 (as supplemented August 18, 2026) | SUMMARY PROSPECTUS 3

PIMCO RAFI Dynamic Multi-Factor U.S. Equity ETF

U.S. common stocks. The S&P 500 Index focuses on the large-cap segment of the U.S. equities market. The RAFI Dynamic Multi-Factor U.S. Index is a supplemental index of the Fund. The RAFI Dynamic Multi-Factor U.S. Index takes time-varying exposures to five return factors; value, low volatility, quality, momentum and size. The Index uses recent and historical metrics to tilt toward factor portfolios which are intended to be particularly attractive on a forward looking basis.

Performance for the Fund is updated daily and quarterly and may be obtained as follows: daily and quarterly updates on the net asset value and performance page at https://www.pimco.com/us/en/product-finder?filters=products=etf.

Calendar Year Total Returns

Best Quarter	June 30, 2020	18.22%
Worst Quarter	March 31, 2020	-24.22%
Year-to-Date	September 30, 2025	14.31%

Average Annual Total Returns (for periods ended 12/31/24)

	1 Year	5 Years	Since Inception	Inception Date
Return Before Taxes	20.09%	11.75%	11.92%	8/31/2017
Return After Taxes on Distributions(1)	19.67%	11.24%	11.37%
Return After Taxes on Distributions and Sales of Fund Shares(1)	12.18%	9.25%	9.56%
S&P 500 Index (reflects no deductions for fees, expenses or taxes)	25.02%	14.53%	14.47%
RAFI Dynamic Multi-Factor U.S. Index (reflects no deductions for fees, expenses or taxes)	20.30%	12.07%	12.26%

After-tax returns are calculated using the highest historical 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, and the 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. In some cases the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.

Investment Manager/Portfolio Managers

PIMCO serves as the investment manager for the Fund. The Fund’s portfolio is jointly and primarily managed by Emmanuel S. Sharef and Alexander Steiner. Dr. Sharef is an Executive Vice President of PIMCO and Mr. Steiner is a Vice President of PIMCO. Dr. Sharef has managed the Fund since August 2026. Mr. Steiner has managed the Fund since August 2022.

Purchase and Sale of Fund Shares

The Fund is an exchange-traded fund (“ETF”). Individual Fund shares may only be purchased and sold on a national securities exchange through a broker-dealer and may not be purchased or redeemed directly with the Fund. The price of Fund shares is based on market price, and because ETF shares trade at market prices rather than net asset value (“NAV”), shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). An investor may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase shares of the Fund (“bid”) and the lowest price a seller is willing to accept for shares (“ask”) when buying or selling shares in the secondary market (the “bid-ask spread”). Recent information, including information about the Fund’s NAV, market price, premiums and discounts, and bid-ask spreads, is included on the Fund’s website at https://www.pimco.com/en-us/investments/etf.

Tax Information

The Fund’s distributions are generally taxable to you as ordinary income, capital gains, or a combination of the two, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account, in which case distributions may be taxable upon withdrawal.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund shares through a broker-dealer or other financial intermediary, PIMCO or other related companies may pay the intermediary for the sale of Fund shares or 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.

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