ThZeal - The Zeal

COLUMBIA FUNDS SERIES TRUST

Summary Prospectus

July 1, 2025

Columbia Small Cap Index Fund

Class	Ticker Symbol
A	NMSAX
Institutional (Class Inst)	NMSCX
Institutional 2 (Class Inst2)	CXXRX
Institutional 3 (Class Inst3)	CSPYX

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, statement of additional information and other information about the Fund online at https://www.columbiathreadneedleus.com/resources/literature. If you hold your Fund shares through a financial intermediary (such as a broker-dealer or bank), you can get this information at no cost by contacting that financial intermediary. If you hold your Fund shares directly with the Fund, you can get this information at no cost by calling 800.345.6611 or by sending an email to serviceinquiries@columbiathreadneedle.com. This Summary Prospectus incorporates by reference the Fund’s prospectus, dated July 1, 2025, and current Statement of Additional Information.

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Investment Objective

Columbia Small Cap Index Fund (the Fund) seeks total return before fees and expenses that corresponds to the total return of the Standard & Poor’s (S&P) SmallCap 600® 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)
	Classes A, Inst, Inst2 and Inst3
Maximum sales charge (load) imposed on purchases (as a % of offering price)	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class Inst	Class Inst2	Class Inst3
Management fees	0.20 %	0.20 %	0.20 %	0.20 %
Distribution and/or service (12b-1) fees	0.25 %	0.00 %	0.00 %	0.00 %
Other expenses	0.00 %	0.00 %	0.00 %	0.00 %
Total annual Fund operating expenses(a)	0.45 %	0.20 %	0.20 %	0.20 %

(a)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

Example

The following 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 illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

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you invest $10,000 in the applicable class of Fund shares for the periods indicated,

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your investment has a 5% return each year, and

■

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$46	$144	$252	$567
Class Inst (whether or not shares are redeemed)	$20	$64	$113	$255
Class Inst2 (whether or not shares are redeemed)	$20	$64	$113	$255
Class Inst3 (whether or not shares are redeemed)	$20	$64	$113	$255

Portfolio Turnover

The Fund may pay 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 23% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks that comprise the S&P SmallCap 600 Index (the Index).

The Fund may invest in derivatives, such as futures (including equity index futures), for cash equitization purposes.

Columbia Small Cap Index Fund

Different common stocks have different weightings in the Index, depending on the amount of stock outstanding and the stock’s current price. In seeking to match the performance of the Index, Columbia Management Investment Advisers, LLC (the Investment Manager) attempts to allocate the Fund’s assets among common stocks in approximately the same weightings as the Index. This is referred to as a passive or indexing approach to investing. As a result of the Fund’s indexing approach to investing, the Fund will typically emphasize within the portfolio those economic sectors emphasized by the Index, such as the financials sector.

The Fund attempts to achieve at least a 95% correlation between the performance of the Index and the Fund’s investment results, before fees and expenses.

Principal Risks

An investment in the Fund involves risks, including Correlation/Tracking Error Risk, Passive Investment Risk, Small-Cap Stock Risk, and Market Risk, among others. Descriptions of these and other principal risks of investing in the Fund are provided below. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and share price may go down. An 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. The significance of any specific risk to an investment in the Fund will vary over time depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information below carefully, because any one or more of these risks may result in losses to the Fund.

Correlation/Tracking Error Risk. The Fund’s value will generally decline when the performance of the securities within the Index declines. A number of factors may affect the Fund’s ability to achieve a high degree of correlation with the Index, and there is no guarantee that the Fund will achieve a high degree of correlation. Failure to achieve a high degree of correlation may prevent the Fund from achieving its investment objective. In addition, the Fund bears management and other expenses and transaction costs in trading securities or other instruments, which the Index does not bear. The Fund, unlike the Index, is subject to regulatory requirements that can limit the Fund’s investments relative to what the Index can hold. Accordingly, the Fund’s performance will likely fail to match the performance of the Index, after taking expenses into account, as well as regulatory limitations. It is not possible to invest directly in an index.

Derivatives Risk. Derivatives may involve significant risks. Derivatives are financial instruments with a value in relation to, or derived from, the value of an underlying asset(s) or other reference, such as an index, rate or other economic indicator (each an underlying reference). Derivatives may include those that are privately placed or otherwise exempt from SEC registration, including certain Rule 144A eligible securities. Derivatives could result in Fund losses if the underlying reference does not perform as anticipated. Use of derivatives is a highly specialized activity that can involve investment techniques, risks, and tax planning different from those associated with more traditional investment instruments. The Fund’s derivatives strategy may not be successful and use of certain derivatives could result in substantial, potentially unlimited, losses to the Fund regardless of the Fund’s actual investment. A relatively small movement in the price, rate or other economic indicator associated with the underlying reference may result in substantial losses for the Fund. Derivatives may be more volatile than other types of investments. The value of derivatives may be influenced by a variety of factors, including national and international political and economic developments. Potential changes to the regulation of the derivatives markets may make derivatives more costly, may limit the market for derivatives, or may otherwise adversely affect the value or performance of derivatives. Derivatives can increase the Fund’s risk exposure to underlying references and their attendant risks, such as credit risk, market risk, foreign currency risk and interest rate risk, while potentially exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.

Derivatives Risk – Futures Contracts Risk. A futures contract is an exchange-traded derivative transaction between two parties in which a buyer (holding the “long” position) agrees to pay a fixed price (or rate) at a specified future date for delivery of an underlying reference from a seller (holding the “short” position). The seller hopes that the market price on the delivery date is less than the agreed upon price, while the buyer hopes for the contrary. Certain futures contract markets are highly volatile, and futures contracts may be illiquid. Futures exchanges may limit fluctuations in futures contract prices by imposing a maximum permissible daily price movement. The Fund may be disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. At or prior to maturity of a futures contract, the Fund may enter into an offsetting contract and may incur a loss to the extent there has been adverse movement in futures contract prices. The liquidity of the futures markets depends on participants entering into offsetting transactions rather than making or taking delivery. To the extent participants make or take delivery, liquidity in the futures market could be reduced. Because of the low margin deposits normally required in futures trading, it is possible that the Fund may employ a high degree of leverage in the portfolio. As a result, a

Columbia Small Cap Index Fund

relatively small price movement in a futures contract may result in substantial losses to the Fund, exceeding the amount of the margin paid. For certain types of futures contracts, losses are potentially unlimited. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s NAV. Futures contracts executed (if any) on foreign exchanges may not provide the same protection as U.S. exchanges. Futures contracts can increase the Fund’s risk exposure to underlying references and their attendant risks, such as credit risk, market risk, foreign currency risk and interest rate risk, while potentially exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.

Issuer Risk. An issuer in which the Fund invests or to which it has exposure may perform poorly or below expectations, and the value of its securities may therefore decline, which may negatively affect the Fund’s performance. Underperformance of an issuer may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters, military confrontations and actions, war, other conflicts, terrorism, disease/virus outbreaks, epidemics or other events, conditions and factors which may impair the value of your investment in the Fund.

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Small-Cap Stock Risk. Investments in small-capitalization companies (small-cap companies) often involve greater risks than investments in larger, more established companies (larger companies) because small-cap companies tend to have less predictable earnings and may lack the management experience, financial resources, product diversification and competitive strengths of larger companies, and securities of small-cap companies may be less liquid and more volatile than the securities of larger companies.

Market Risk. The Fund may incur losses due to declines in the value of one or more securities in which it invests. These declines may be due to factors affecting a particular issuer, or the result of, among other things, political, regulatory, market, economic or social developments affecting the relevant market(s) more generally. In addition, turbulence in financial markets and reduced liquidity in equity, credit and/or fixed income markets may negatively affect many issuers, which could adversely affect the Fund’s ability to price or value hard-to-value assets in thinly traded and closed markets and could cause significant redemptions and operational challenges. Global economies and financial markets are increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market. These risks may be magnified if certain events or developments adversely interrupt the global supply chain; in these and other circumstances, such risks might affect companies worldwide. As a result, local, regional or global events such as terrorism, war, other conflicts, natural disasters, disease/virus outbreaks and epidemics or other public health issues, recessions, depressions or other events – or the potential for such events – could have a significant negative impact on global economic and market conditions.

Passive Investment Risk. The Fund is not actively managed and may be affected by a general decline in market segments related to its Index’s investment exposures. The Fund invests in securities or instruments included in, or believed by the portfolio manager to be representative of, the Index regardless of their investment merits. The Fund does not seek temporary defensive positions when markets decline or appear overvalued.

Sector Risk. At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a related group of industries within one or more economic sectors, including the financials sector. The Fund generally invests in issuers, including to concentrate its investments in issuers conducting business in a related group of industries, to approximately the same extent as the Index. Companies in the same sector may be similarly affected by economic, regulatory, political or market events or conditions, which may make the Fund vulnerable to unfavorable developments in that group of industries or economic sector.

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Financials Sector. The Fund is vulnerable to the particular risks that may affect companies in the financials sector. Companies in the financials sector are subject to certain risks, including the risk of regulatory change, decreased liquidity in credit markets and unstable interest rates. Such companies may have concentrated portfolios, such as a high level of loans to one or more industries or sectors, which makes them vulnerable to economic conditions that affect such industries or sectors. Performance of such companies may be affected by competitive pressures and exposure to investments, agreements and counterparties, including credit products that, under certain circumstances, may lead to losses (e.g., subprime loans). Companies in the financials sector are subject to extensive governmental regulation that may limit the amount and types of loans and other financial commitments they can make, and the interest rates and fees they may charge. In addition, profitability of such companies is largely dependent upon the availability and the cost of capital.

Columbia Small Cap Index Fund

Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. The bar chart shows how the Fund’s Class A share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with a broad measure of market performance, as well as another measure of performance for markets in which the Fund may invest.

Effective August 1, 2024, the Fund compares its performance to the Russell 3000® Index, a broad-based performance index, as required by new regulatory requirements. The Fund’s performance also continues to be compared to its prior benchmark, which management believes more closely represents the market sectors and/or asset classes in which the Fund primarily invests.

The performance of one or more share classes shown in the table below begins before the indicated inception date for such share class. The returns shown for each such share class include the returns of the Fund’s Class A shares for periods prior to its inception date.

Except for differences in annual returns resulting from differences in expenses and sales charges (where applicable), the share classes of the Fund would have substantially similar annual returns because all share classes of the Fund invest in the same portfolio of securities.

The after-tax returns shown in the Average Annual Total Returns table below are calculated using the highest historical individual U.S. federal marginal income tax rates in effect during the period indicated in the table and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-advantaged accounts such as 401(k) plans or Individual Retirement Accounts (IRAs). The after-tax returns are shown only for Class A shares and will vary for other share classes.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting columbiathreadneedleus.com.

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	Best	4th Quarter 2020	31.13%
	Worst	1st Quarter 2020	-32.69%

Year to Date return as of March 31, 2025: -9.04%

Average Annual Total Returns (for periods ended December 31, 2024)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class A	10/15/1996
returns before taxes		8.23%	7.86%	8.45%
returns after taxes on distributions		4.67%	5.77%	6.36%
returns after taxes on distributions and sale of Fund shares		7.43%	6.00%	6.42%
Class Inst returns before taxes	10/15/1996	8.52%	8.13%	8.73%
Class Inst2 returns before taxes	11/08/2012	8.48%	8.13%	8.73%
Class Inst3 returns before taxes	03/01/2017	8.50%	8.13%	8.67%
S&P SmallCap 600® Index (reflects no deductions for fees, expenses or taxes)		8.70%	8.36%	8.96%
Russell 3000® Index (reflects no deductions for fees, expenses or taxes)		23.81%	13.86%	12.55%

Columbia Small Cap Index Fund

Fund Management

Investment Manager: Columbia Management Investment Advisers, LLC

Portfolio Management	Title	Role with Fund	Managed Fund Since
Christopher Lo, CFA	Senior Portfolio Manager	Portfolio Manager	2014

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online	Regular Mail	Express Mail	By Telephone
columbiathreadneedleus.com/investor/	Columbia Management Investment Services Corp. P.O. Box 219104 Kansas City, MO 64121-9104	Columbia Management Investment Services Corp. 801 Pennsylvania Ave., STE. 219104 Kansas City, MO 64105-1307	800.422.3737

You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. If you maintain your account with a broker-dealer or other financial intermediary, you must contact that financial intermediary to buy, sell or exchange shares of the Fund through your account with the intermediary.

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than Systematic Investment Plan accounts (as described in the Fund’s Prospectus)	For Systematic Investment Plan accounts
Class A	All accounts other than IRAs	$2,000	$100
Class A	IRAs	$1,000	$100
Class Inst	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100
Class Inst2	All eligible accounts	None	N/A
Class Inst3	All eligible accounts	$0, $1,000, $2,000 or $1 million depending upon the category of eligible investor	$100 (for certain eligible investors)

More information about these minimums can be found in the Buying, Selling and Exchanging Shares - Buying Shares section of the prospectus. There is no minimum additional investment for any share class.

Columbia Small Cap Index Fund

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income, qualified dividend income or capital gains, unless you are investing through a tax-advantaged account, such as a 401(k) plan or an IRA. If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies — including Columbia Management Investment Advisers, LLC (the Investment Manager), Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) — may 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 financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

Columbia Small Cap Index Fund

Columbia Threadneedle Investments is the global brand name of the Columbia and Threadneedle group of companies.

The Fund is distributed by Columbia Management Investment Distributors, Inc., 290 Congress Street, Boston, MA 02210.

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