Columbia Funds Series Trust I

Summary Prospectus

September 1, 2020

Columbia Total Return Bond Fund

Class		Ticker Symbol
A		LIBAX
Advisor (Class Adv)		CBNRX
C		LIBCX
Institutional (Class Inst)		SRBFX
Institutional 2 (Class Inst2)		CTBRX
Institutional 3 (Class Inst3)		CTBYX
R		CIBRX

Beginning on January 1, 2021, as permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund's annual and semiannual 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 Fund's website (columbiathreadneedleus.com/investor/), and each time a report is posted you will be notified by mail and provided with a website address to access the report.

If you have already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically at any time by contacting your financial intermediary (such as a broker-dealer or bank) or, for Fund shares held directly with the Fund, by calling 800.345.6611 or by enrolling in “eDelivery” by logging into your account at columbiathreadneedleus.com/investor/.

You may elect to receive all future shareholder reports in paper free of charge. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue receiving paper copies of your shareholder reports. If you invest directly with the Fund, you can call 800.345.6611 to let the Fund know you wish to continue receiving paper copies of your shareholder reports. Your election to receive paper reports will apply to all Columbia Funds held in your account if you invest through a financial intermediary or all Columbia Funds held with the fund complex if you invest directly with the Fund.

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 September 1, 2020, 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 Total Return Bond Fund (the Fund) seeks total return, consisting of current income and capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. An investor transacting in a class of Fund shares without any front-end sales charge, contingent deferred sales charge, or other asset-based fee for sales or distribution may be required to pay a commission to the financial intermediary for effecting such transactions. Such commission rates are set by the financial intermediary and are not reflected in the tables or the example below. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information is available about these and other sales charge discounts and waivers from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 31 of the Fund’s prospectus, in Appendix A to the prospectus beginning on page A-1 and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes Adv, Inst, Inst2, Inst3 and R
Maximum sales charge (load) imposed on purchases (as a % of offering price)	3.00%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	1.00% ^(b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class Adv	Class C	Class Inst	Class Inst2	Class Inst3	Class R
Management fees	0.49%	0.49%	0.49%	0.49%	0.49%	0.49%	0.49%
Distribution and/or service (12b-1) fees	0.25%	0.00%	1.00%	0.00%	0.00%	0.00%	0.50%
Other expenses	0.16%	0.16%	0.16%	0.16%	0.09%	0.04%	0.16%
Total annual Fund operating expenses	0.90%	0.65%	1.65%	0.65%	0.58%	0.53%	1.15%
Less: Fee waivers and/or expense reimbursements^(c)	(0.15%)	(0.15%)	(0.15%)	(0.15%)	(0.15%)	(0.15%)	(0.15%)
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	0.75%	0.50%	1.50%	0.50%	0.43%	0.38%	1.00%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.
(c)	Columbia Management Investment Advisers, LLC and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, acquired fund fees and expenses, and infrequent and/or unusual expenses) through August 31, 2021, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.75% for Class A, 0.50% for Class Adv, 1.50% for Class C, 0.50% for Class Inst, 0.43% for Class Inst2, 0.38% for Class Inst3 and 1.00% for Class R. The fee waivers and/or expense reimbursements shown in the table for Class Inst2 and Class Inst3 also reflect the contractual agreement of the Fund’s transfer agent to waive fees and/or to reimburse expenses through August 31, 2021, unless sooner terminated at the sole discretion of the Fund’s Board, so that the Fund’s transfer agency fees do not exceed the annual rates of 0.05% for Class Inst2 and 0.00% for Class Inst3.

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:

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

1	Columbia Total Return Bond Fund

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire as indicated in the preceding table, they are only reflected in the 1 year example and the first year of the other examples. 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)	$374	$564	$769	$1,361
Class Adv (whether or not shares are redeemed)	$ 51	$193	$347	$ 796
Class C (assuming redemption of all shares at the end of the period)	$253	$506	$883	$1,942
Class C (assuming no redemption of shares)	$153	$506	$883	$1,942
Class Inst (whether or not shares are redeemed)	$ 51	$193	$347	$ 796
Class Inst2 (whether or not shares are redeemed)	$ 44	$171	$309	$ 711
Class Inst3 (whether or not shares are redeemed)	$ 39	$155	$281	$ 650
Class R (whether or not shares are redeemed)	$102	$351	$619	$1,384

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 272% 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 bonds, notes and other debt instruments, including derivatives relating to such investments. The Fund may invest up to 35% of its net assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high-yield” investments or “junk” bonds). The Fund may invest in debt instruments issued by U.S. and non-U.S. governments, their agencies, authorities or instrumentalities, U.S. and non-U.S. corporate or other non-governmental entities, as well as mortgage- and other asset-backed securities.

The Fund generally expects to maintain an effective duration of +/- 2 years relative to the Bloomberg Barclays U.S. Aggregate Bond Index.

The Fund may invest in derivatives, such as futures (including interest rate futures) and swaps (including credit default swaps, credit default swap indexes, and interest rate swaps) for hedging and investment purposes, and to manage interest rate and/or credit exposure of the Fund.

The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.

The Fund’s investments in mortgage-related securities include investments in stripped mortgage-backed securities such as interest-only (IO) and principal-only (PO) securities.

The Fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions.

The Fund’s investment strategy may involve the frequent trading of portfolio securities.

Principal Risks

An investment in the Fund involves risks, including Interest Rate Risk, Credit Risk, Market Risk, and Mortgage- and Other Asset-Backed Securities 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.

Active Management Risk. Due to its active management, the Fund could underperform its benchmark index and/or other funds with similar investment objectives and/or strategies.

Columbia Total Return Bond Fund

Changing Distribution Level Risk. The Fund normally expects to receive income which may include interest, dividends and/or capital gains, depending upon its investments. The distribution amounts paid by the Fund will vary and generally depend on the amount of income the Fund earns (less expenses) on its portfolio holdings, and capital gains or losses it recognizes. A decline in the Fund’s income or net capital gains arising from its investments may reduce its distribution level.

Counterparty Risk. Counterparty risk is the risk that a counterparty to a transaction in a financial instrument held by the Fund or by a special purpose or structured vehicle invested in by the Fund may become insolvent or otherwise fail to perform its obligations. As a result, the Fund may obtain no or limited recovery of its investment, and any recovery may be significantly delayed.

Credit Risk. Credit risk is the risk that the value of loans or other debt instruments may decline if the borrower or the issuer thereof defaults or otherwise becomes unable or unwilling, or is perceived to be unable or unwilling, to honor its financial obligations, such as making payments to the Fund when due. Credit rating agencies assign credit ratings to certain loans and debt instruments to indicate their credit risk. Unless otherwise provided in the Fund’s Principal Investment Strategies, investment grade debt instruments are those rated at or above BBB- by S&P Global Ratings, or equivalently rated by Moody’s Investors Service, Inc. or Fitch Ratings, Inc., or, if unrated, determined by the management team to be of comparable quality. Conversely, below investment grade (commonly called “high-yield” or “junk”) debt instruments are those rated below BBB- by S&P Global Ratings, or equivalently rated by Moody’s Investors Service, Inc. or Fitch Ratings, Inc., or, if unrated, determined by the management team to be of comparable quality. A rating downgrade by such agencies can negatively impact the value of such instruments. Lower quality or unrated loans or instruments held by the Fund may present increased credit risk as compared to higher-rated loans or instruments. Non-investment grade loans or debt instruments may be subject to greater price fluctuations and are more likely to experience a default than investment grade loans or debt instruments and therefore may expose the Fund to increased credit risk. If the Fund purchases unrated loans or instruments, or if the ratings of loans or instruments held by the Fund are lowered after purchase, the Fund will depend on analysis of credit risk more heavily than usual. If the issuer of a loan declares bankruptcy or is declared bankrupt, there may be a delay before the Fund can act on the collateral securing the loan, which may adversely affect the Fund. Further, there is a risk that a court could take action with respect to a loan that is adverse to the holders of the loan. Such actions may include invalidating the loan, the lien on the collateral, the priority status of the loan, or ordering the refund of interest previously paid by the borrower. Any such actions by a court could adversely affect the Fund’s performance. A default or expected default of a loan could also make it difficult for the Fund to sell the loan at a price approximating the value previously placed on it. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel. This may increase the Fund’s operating expenses and adversely affect its NAV. Loans that have a lower priority for repayment in an issuer’s capital structure may involve a higher degree of overall risk than more senior loans of the same borrower.

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 loss 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 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

3	Columbia Total Return Bond Fund

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 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 also exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.

Derivatives Risk – Swaps Risk. In a typical swap transaction, two parties agree to exchange the return earned on a specified underlying reference for a fixed return or the return from another underlying reference during a specified period of time. Swaps may be difficult to value and may be illiquid. Swaps could result in Fund losses if the underlying asset or reference does not perform as anticipated. Swaps create significant investment leverage such that a relatively small price movement in a swap may result in immediate and substantial losses to the Fund. The Fund may only close out a swap with its particular counterparty, and may only transfer a position with the consent of that counterparty. Certain swaps, such as short swap transactions and total return swaps, have the potential for unlimited losses, regardless of the size of the initial investment. Swaps 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 also exposing the Fund to correlation risk, counterparty risk, hedging risk, inflation risk, leverage risk, liquidity risk, pricing risk and volatility risk.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including political, regulatory, economic, social, diplomatic and other conditions or events (including, for example, military confrontations, war, terrorism and disease/virus outbreaks and epidemics), occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. In addition, foreign governments may impose withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. The performance of the Fund may also be negatively affected by fluctuations in a foreign currency's strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk. When purchasing mortgage-backed securities in the “to be announced” (TBA) market (MBS TBAs), the seller agrees to deliver mortgage-backed securities for an agreed upon price on an agreed upon date, but may make no guarantee as to the specific securities to be delivered. In lieu of taking delivery of mortgage-backed securities, the Fund could enter into dollar rolls, which are transactions in which the Fund sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities the Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase the Fund’s portfolio turnover rate. If the Fund reinvests the proceeds of the security sold, the Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk). MBS TBAs and dollar rolls are subject to the risk that the counterparty to the transaction may not perform or be unable to perform in accordance with the terms of the instrument.

Frequent Trading Risk. The portfolio managers may actively and frequently trade investments in the Fund's portfolio to carry out its investment strategies. Frequent trading of investments increases the possibility that the Fund, as relevant, will realize taxable capital gains (including short-term capital gains, which are generally taxable to shareholders at higher rates than long-term capital gains for U.S. federal income tax purposes), which could reduce the Fund's after-tax return. Frequent trading can also mean higher brokerage and other transaction costs, which could reduce the Fund's return. The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund’s performance.

Columbia Total Return Bond Fund

High-Yield Investments Risk. Securities and other debt instruments held by the Fund that are rated below investment grade (commonly called “high-yield” or “junk” bonds) and unrated debt instruments of comparable quality expose the Fund to a greater risk of loss of principal and income than a fund that invests solely or primarily in investment grade debt instruments. In addition, these investments have greater price fluctuations, are less liquid and are more likely to experience a default than higher-rated debt instruments. High-yield debt instruments are considered to be predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal.

Interest Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of loans and other debt instruments tend to fall, and if interest rates fall, the values of loans and other debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. Interest rate declines also may increase prepayments of debt obligations, which, in turn, would increase prepayment risk. Very low or negative interest rates may impact the Fund’s yield and may increase the risk that, if followed by rising interest rates, the Fund’s performance will be negatively impacted. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases in interest rates. Such actions may negatively affect the value of debt instruments held by the Fund, resulting in a negative impact on the Fund's performance and NAV. Debt instruments with floating coupon rates are typically less sensitive to interest rate changes, but these debt instruments may decline in value if their coupon rates do not rise as much as, or keep pace with, yields on such types of debt instruments. Because rates on certain floating rate loans and other debt instruments reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause fluctuations in the Fund’s NAV. Any interest rate increases could cause the value of the Fund’s investments in debt instruments to decrease. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses.

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 loans or 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, war, terrorism, disease/virus outbreaks, epidemics or other events, conditions and factors which may impair the value of an investment in the Fund.

Leverage Risk. Leverage occurs when the Fund increases its assets available for investment using borrowings, derivatives, or similar instruments or techniques. Use of leverage can produce volatility and may exaggerate changes in the NAV of Fund shares and in the return on the Fund’s portfolio, which may increase the risk that the Fund will lose more than it has invested. If the Fund uses leverage, through the purchase of particular instruments such as derivatives, the Fund may experience capital losses that exceed the net assets of the Fund. Leverage can create an interest expense that may lower the Fund's overall returns. Leverage presents the opportunity for increased net income and capital gains, but may also exaggerate the Fund’s volatility and risk of loss. There can be no guarantee that a leveraging strategy will be successful.

LIBOR Replacement Risk. The elimination of London Inter-Bank Offered Rate (LIBOR), among other “inter-bank offered” reference rates, may adversely affect the interest rates on, and value of, certain Fund investments for which the value is tied to LIBOR. The U.K. Financial Conduct Authority has announced that it intends to stop compelling or inducing banks to submit LIBOR rates after 2021. However, it remains unclear if LIBOR will continue to exist in its current, or a modified, form. Alternatives to LIBOR have been established or are in development in most major currencies including the Secured Overnight Financing Rate (SOFR) that is intended to replace U.S. dollar LIBOR. Markets are slowly developing in response to these new reference rates. Uncertainty related to the liquidity impact of the change in rates, and how to appropriately adjust these rates at the time of transition, poses risks for the Fund. These risks are likely to persist until new reference rates and fallbacks for both legacy and new instruments and contracts are commercially accepted and market practices become settled.

Liquidity Risk. Liquidity risk is the risk associated with any event, circumstance, or characteristic of an investment or market that negatively impacts the Fund’s ability to sell, or realize the proceeds from the sale of, an investment at a desirable time or price. Liquidity risk may arise because of, for example, a lack of marketability of the investment, which means that when seeking to sell its portfolio investments, the Fund could find that selling is more difficult than anticipated, especially during times of high market volatility. Decreases in the number of financial institutions, including banks and broker-dealers, willing to make markets (match up sellers and buyers) in the Fund’s investments or decreases in their capacity or willingness to trade such investments may increase the Fund’s exposure to this risk. The debt market has experienced considerable growth, and financial institutions making markets in instruments

5	Columbia Total Return Bond Fund

purchased and sold by the Fund (e.g., bond dealers) have been subject to increased regulation. The impact of that growth and regulation on the ability and willingness of financial institutions to engage in trading or “making a market” in such instruments remains unsettled. Certain types of investments, such as lower-rated securities or those that are purchased and sold in over-the-counter markets, may be especially subject to liquidity risk. Securities or other assets in which the Fund invests may be traded in the over-the-counter market rather than on an exchange and therefore may be more difficult to purchase or sell at a fair price, which may have a negative impact on the Fund’s performance. Market participants attempting to sell the same or a similar instrument at the same time as the Fund could exacerbate the Fund’s exposure to liquidity risk. The Fund may have to accept a lower selling price for the holding, sell other liquid or more liquid investments that it might otherwise prefer to hold (thereby increasing the proportion of the Fund’s investments in less liquid or illiquid securities), or forego another more appealing investment opportunity. The liquidity of Fund investments may change significantly over time and certain investments that were liquid when purchased by the Fund may later become illiquid, particularly in times of overall economic distress. Changing regulatory, market or other conditions or environments (for example, the interest rate or credit environments) may also adversely affect the liquidity and the price of the Fund's investments. Judgment plays a larger role in valuing illiquid or less liquid investments as compared to valuing liquid or more liquid investments. Price volatility may be higher for illiquid or less liquid investments as a result of, for example, the relatively less frequent pricing of such securities (as compared to liquid or more liquid investments). Generally, the less liquid the market at the time the Fund sells a portfolio investment, the greater the risk of loss or decline of value to the Fund. Overall market liquidity and other factors can lead to an increase in redemptions, which may negatively impact Fund performance and NAV, including, for example, if the Fund is forced to sell investments in a down market.

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, including causing difficulty in assigning prices to hard-to-value assets in thinly traded and closed markets, 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, 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.

The coronavirus disease 2019 (COVID-19) public health crisis has become a pandemic that has resulted in, and may continue to result in, significant global economic and societal disruption and market volatility due to disruptions in market access, resource availability, facilities operations, imposition of tariffs, export controls and supply chain disruption, among others. Such disruptions may be caused, or exacerbated by, quarantines and travel restrictions, workforce displacement and loss in human and other resources. The uncertainty surrounding the magnitude, duration, reach, costs and effects of the global pandemic, as well as actions that have been or could be taken by governmental authorities or other third parties, present unknowns that are yet to unfold. The impacts, as well as the uncertainty over impacts to come, of COVID-19 – and any other infectious illness outbreaks, epidemics and pandemics that may arise in the future – could negatively affect global economies and markets in ways that cannot necessarily be foreseen. In addition, the impact of infectious illness outbreaks and epidemics in emerging market countries may be greater due to generally less established healthcare systems, governments and financial markets. Public health crises caused by the COVID-19 outbreak may exacerbate other pre-existing political, social and economic risks in certain countries or globally. The disruptions caused by COVID-19 could prevent the Fund from executing advantageous investment decisions in a timely manner and negatively impact the Fund’s ability to achieve its investment objective. Any such event(s) could have a significant adverse impact on the value and risk profile of the Fund.

Mortgage- and Other Asset-Backed Securities Risk. The value of any mortgage-backed and other asset-backed securities including collateralized debt obligations and collateralized loan obligations, if any, held by the Fund may be affected by, among other things, changes or perceived changes in: interest rates; factors concerning the interests in and structure of the issuer or the originator of the mortgages or other assets; the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements; or the market's assessment of the quality of underlying assets. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed by the full faith and credit of a particular U.S. Government agency, authority, enterprise or instrumentality, and some, but not all, are also insured or guaranteed by the U.S. Government. Mortgage-backed securities issued by non-governmental issuers (such as commercial banks,

Columbia Total Return Bond Fund

savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may entail greater risk than obligations guaranteed by the U.S. Government. Mortgage- and other asset-backed securities are subject to liquidity risk and prepayment risk. A decline or flattening of housing values may cause delinquencies in mortgages (especially sub-prime or non-prime mortgages) underlying mortgage-backed securities and thereby adversely affect the ability of the mortgage-backed securities issuer to make principal and/or interest payments to mortgage-backed securities holders, including the Fund. Rising or high interest rates tend to extend the duration of mortgage- and other asset-backed securities, making their prices more volatile and more sensitive to changes in interest rates.

Prepayment and Extension Risk. Prepayment and extension risk is the risk that a loan, bond or other security or investment might, in the case of prepayment risk, be called or otherwise converted, prepaid or redeemed before maturity and, in the case of extension risk, that the investment might not be called as expected. In the case of prepayment risk, if the investment is converted, prepaid or redeemed before maturity, the portfolio managers may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to the Fund. In the case of mortgage- or other asset-backed securities, as interest rates decrease or spreads narrow, the likelihood of prepayment increases. Conversely, extension risk is the risk that an unexpected rise in interest rates will extend the life of a mortgage- or other asset-backed security beyond the prepayment time. If the Fund’s investments are locked in at a lower interest rate for a longer period of time, the portfolio managers may be unable to capitalize on securities with higher interest rates or wider spreads.

Reinvestment Risk. Reinvestment risk arises when the Fund is unable to reinvest income or principal at the same or at least the same return it is currently earning.

Rule 144A and Other Exempted Securities Risk. The Fund may invest in privately placed and other securities or instruments exempt from SEC registration (collectively “private placements”), subject to certain regulatory restrictions. In the U.S. market, private placements are typically sold only to qualified institutional buyers, or qualified purchasers, as applicable. An insufficient number of buyers interested in purchasing private placements at a particular time could adversely affect the marketability of such investments and the Fund might be unable to dispose of them promptly or at reasonable prices, subjecting the Fund to liquidity risk. The Fund’s holdings of private placements may increase the level of Fund illiquidity if eligible buyers are unable or unwilling to purchase them at a particular time. Issuers of Rule 144A eligible securities are required to furnish information to potential investors upon request. However, the required disclosure is much less extensive than that required of public companies and is not publicly available since the offering information is not filed with the SEC. Further, issuers of Rule 144A eligible securities can require recipients of the offering information (such as the Fund) to agree contractually to keep the information confidential, which could also adversely affect the Fund’s ability to dispose of the security.

Sovereign Debt Risk. A sovereign debtor’s willingness or ability to repay principal and pay interest in a timely manner may be affected by a variety of factors, including its cash flow situation, the extent of its reserves, the availability of sufficient foreign exchange on the date a payment is due, the relative size of the debt service burden to the economy as a whole, the sovereign debtor’s policy toward international lenders, and the political constraints to which a sovereign debtor may be subject.

Stripped Mortgage-Backed Securities Risk. Stripped mortgage-backed securities are a type of mortgage-backed security that receive differing proportions of the interest and principal payments from the underlying assets. Generally, there are two classes of stripped mortgage-backed securities: Interest Only (IO) and Principal Only (PO). IOs entitle the holder to receive distributions consisting of all or a portion of the interest on the underlying pool of mortgage loans or mortgage-backed securities. POs entitle the holder to receive distributions consisting of all or a portion of the principal of the underlying pool of mortgage loans or mortgage-backed securities. The cash flows and yields on IOs and POs are extremely sensitive to the rate of principal payments (including prepayments) on the underlying mortgage loans or mortgage-backed securities. A rapid rate of principal payments may adversely affect the yield to maturity of IOs. A slow rate of principal payments may adversely affect the yield to maturity of POs. If prepayments of principal are greater than anticipated, an investor in IOs may incur substantial losses. If prepayments of principal are slower than anticipated, the yield on a PO will be affected more severely than would be the case with a traditional mortgage-backed security.

U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government.

7	Columbia Total Return Bond 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 (without sales charges) has varied for each full calendar year shown. If the sales charges were reflected, returns shown would be lower. The table below the bar chart compares the Fund’s returns (after applicable sales charges shown in the Shareholder Fees table in this prospectus) for the periods shown with a broad measure of market performance.

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 Inst shares (adjusted to reflect the higher class-related operating expenses of such share classes, where applicable) for periods prior to its inception date. Share classes with expenses that are higher than Class Inst shares will have performance that is lower than Class Inst shares. 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 performance prior to February 19, 2016 reflects returns achieved pursuant to different principal investment strategies. If the Fund’s current strategies had been in place for the prior periods, results shown may have been different.

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	_{1st Quarter 2019}	_3.59%
	_Worst	_{2nd Quarter 2013}	_-2.72%

*	Year to Date return as of June 30, 2020: 6.31%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2019)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class A	07/31/2000
returns before taxes		5.80%	2.80%	3.74%
returns after taxes on distributions		4.03%	1.44%	2.37%
returns after taxes on distributions and sale of Fund shares		3.49%	1.56%	2.33%
Class Adv returns before taxes	11/08/2012	9.44%	3.70%	4.32%
Class C returns before taxes	02/01/2002	7.35%	2.67%	3.37%
Class Inst returns before taxes	12/05/1978	9.43%	3.68%	4.32%
Class Inst2 returns before taxes	11/08/2012	9.53%	3.75%	4.37%
Class Inst3 returns before taxes	11/08/2012	9.57%	3.80%	4.41%
Class R returns before taxes	01/23/2006	8.89%	3.16%	3.81%
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deductions for fees, expenses or taxes)		8.72%	3.05%	3.75%

Columbia Total Return Bond Fund

Fund Management

Investment Manager: Columbia Management Investment Advisers, LLC

Portfolio Manager	Title	Role with Fund	Managed Fund Since
Jason Callan	Senior Portfolio Manager and Head of Structured Assets	Lead Portfolio Manager	2016
Gene Tannuzzo, CFA	Deputy Global Head of Fixed Income and Senior Portfolio Manager	Portfolio Manager	2017

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. c/o DST Asset Manager Solutions, Inc. 430 W 7^th Street, Suite 219104 Kansas City, MO 64105-1407		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	For systematic investment plan accounts
Classes A & C	All accounts other than IRAs	$2,000	$100
Classes A & C	IRAs	$1,000	$100
Classes Adv & Inst	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100
Classes Inst2 & R	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.

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 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.

9	Columbia Total Return Bond Fund

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

columbiathreadneedleus.com

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