Columbia Funds Series Trust I

Summary Prospectus

June 1, 2018

Columbia Diversified Real Return Fund

Class		Ticker Symbol
A		CDRAX
Advisor (Class Adv)^(a)		CDRRX
C		CDRCX
Institutional (Class Inst)^(a)		CDRZX
Institutional 2 (Class Inst2)^(a)		CDRFX
Institutional 3 (Class Inst3)^(a)		CDRYX
T		CDTWX

(a)	Prior to November 1, 2017, Class Adv shares were known as Class R4 shares, Class Inst shares were known as Class Z shares, Class Inst2 shares were known as Class R5 shares, and Class Inst3 shares were known as Class Y shares.

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus, statement of additional information and other information about the Fund online at https://www.columbiathreadneedleus.com/resources/literature. You can also 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 June 1, 2018, 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 Diversified Real Return Fund (the Fund) seeks to provide shareholders with total return that exceeds the rate of inflation over the long term.

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. The front-end sales charge applicable to Class T shares is a per-transaction charge, meaning that separate orders will not be aggregated for purposes of calculating the rate of the sales charge payable. 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 36 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	Class T	Classes Adv, Inst, Inst2 and Inst3
Maximum sales charge (load) imposed on purchases (as a % of offering price)	4.75%	None	2.50%	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	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 T
Management fees	0.14%	0.14%	0.14%	0.14%	0.14%	0.14%	0.14%
Distribution and/or service (12b-1) fees	0.25%	0.00%	1.00%	0.00%	0.00%	0.00%	0.25%
Other expenses^(c)	16.82%	16.82%	16.82%	16.82%	16.83%	16.78%	16.82%
Acquired fund fees and expenses	0.55%	0.55%	0.55%	0.55%	0.55%	0.55%	0.55%
Total annual Fund operating expenses^(d)	17.76%	17.51%	18.51%	17.51%	17.52%	17.47%	17.76%
Less: Fee waivers and/or expense reimbursements^(e)	(16.61%)	(16.61%)	(16.61%)	(16.61%)	(16.60%)	(16.60%)	(16.61%)
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	1.15%	0.90%	1.90%	0.90%	0.92%	0.87%	1.15%

(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)	Other expenses have been restated to reflect current fees paid by the Fund.
(d)	“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 “Total Net Expenses” shown in the Financial Highlights section of this prospectus because “Total Net Expenses” do not include acquired fund fees and expenses.
(e)	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, dividend expenses and borrowing costs on securities sold short, interest, taxes, acquired fund fees and expenses, and infrequent and/or unusual expenses) through May 31, 2019, 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 0.60% for Class A, 0.35% for Class Adv, 1.35% for Class C, 0.35% for Class Inst, 0.37% for Class Inst2, 0.32% for Class Inst3 and 0.60% for Class T.

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

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

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 (based on estimated Fund expenses) would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$587	$3,666	$6,010	$9,703
Class Adv (whether or not shares are redeemed)	$ 92	$3,296	$5,748	$9,649
Class C (assuming redemption of all shares at the end of the period)	$293	$3,511	$5,994	$9,797
Class C (assuming no redemption of shares)	$193	$3,511	$5,994	$9,797
Class Inst (whether or not shares are redeemed)	$ 92	$3,296	$5,748	$9,649
Class Inst2 (whether or not shares are redeemed)	$ 94	$3,299	$5,751	$9,650
Class Inst3 (whether or not shares are redeemed)	$ 89	$3,288	$5,738	$9,642
Class T (whether or not shares are redeemed)	$364	$3,517	$5,916	$9,696

Portfolio Turnover

The Fund and underlying funds (including exchange-traded funds (ETFs)) may pay transaction costs, such as commissions, when they buy and sell securities (or “turn over” their portfolios). The Fund will indirectly bear the expenses associated with portfolio turnover of the underlying funds. A higher portfolio turnover rate may indicate higher transaction costs. 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 36% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund pursues its investment objective by allocating its assets to achieve exposure to inflation-linked debt securities, investments that provide economic exposure to the performance of commodities markets (commodity-linked investments) and floating rate loans and other floating rate debt securities (floating rate investments), as well as other investments.

The Fund’s investment exposure to inflation-linked (or inflation-protected) debt securities may include exposure to investments issued by the U.S. Government, non-U.S. governments, quasi-governmental organizations, agencies, instrumentalities, supranational entities and/or companies. Inflation-linked debt securities are fixed-income securities that are structured to provide protection against inflation. The Fund’s investment exposure to commodity-linked investments may include investment in an underlying fund, Columbia Commodity Strategy Fund, that is designed to provide exposure to the investment return of assets that trade in the commodities markets, without investing directly in physical commodities. The Fund’s investment exposure to floating rate investments may include investments in floating rate loans (including senior secured floating rate loans), which are debt obligations of companies and other similar entities that have interest rates that adjust or “float” periodically. These debt obligations may be of any quality, including those rated below investment grade by recognized rating agencies (similar to “junk bonds”) or, if unrated, considered to be of comparable quality. While the Fund seeks to achieve commodities exposure indirectly through investment in an underlying fund, the Fund may seek to achieve other exposures directly or indirectly through investment in affiliated funds, including Columbia Inflation Protected Securities Fund, Columbia Floating Rate Fund and any other Columbia fund that offers a desired exposure, as well as in unaffiliated funds, including exchange-traded funds (ETFs). Certain of these investments will include exposure to alternative investment strategies (e.g., Columbia Commodity Strategy Fund, a registered commodity pool).

The Fund’s assets may also be allocated to equity (common and preferred stock), convertible and other fixed income securities of U.S. and international issuers, which include developed, developing and emerging market issuers, investments of any market capitalization, and investments of any sector/industry exposure, including, for example, exposure to real estate securities. The Fund’s fixed income investments may be of any maturity or quality, including instruments that are rated below investment-grade (commonly referred to as “high yield securities” or “junk bonds”) or, if unrated, are deemed to be of comparable quality. The Fund may invest in the above instruments directly or indirectly through investments in unaffiliated or affiliated funds, including Columbia High Yield Bond Fund, Columbia Income Opportunities Fund and Columbia Limited Duration Credit Fund, among other available funds. The Fund does not seek to maintain a particular dollar-weighted average maturity. The Fund may also hold/invest in cash, money

Columbia Diversified Real Return Fund

market instruments (which may include investments in one or more affiliated or unaffiliated money market funds or similar vehicles) or other high-quality, short-term investments, including for the purpose of covering its obligations with respect to, or that may result from, the Fund’s investments in derivatives.

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 (the 1933 Act), subject to liquidity determinations and certain regulatory restrictions.

Principal Risks

An investment in the Fund involves risks, including specific risks relating to the investment in the Fund based on its investment process and its "fund-of-funds" structure, as well as specific risks related to the underlying funds in which it invests that in the aggregate are principal risks to the Fund, including among others, those described below. More information about underlying funds, including their principal risks, is available in their prospectuses, which are incorporated by reference into this prospectus. This prospectus is not an offer for any of the underlying funds. 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.

Allocation Risk. Because the Fund uses an asset allocation strategy in pursuit of its investment objective, there is a risk that the Fund's allocation among securities, instruments, investment styles and market exposures will cause the Fund's shares to lose value or cause the Fund to underperform other funds with similar investment objectives and/or strategies, or that the investments themselves will not produce the returns expected.

Alternative Strategies Investment Risk. An investment in alternative investment strategies (Alternative Strategies), whether through direct investment or through one or more underlying funds that use Alternative Strategies, involves risks, which may be significant. Alternative Strategies may include strategies, instruments or other assets, such as derivatives, that seek investment returns uncorrelated with the broad equity and fixed income/debt markets, as well as those providing exposure to other markets (such as commodity markets), including but not limited to absolute (positive) return strategies. Alternative Strategies may fail to achieve their desired performance, market or other exposure, or their returns (or lack thereof) may be more correlated with the broad equity and/or fixed income/debt markets than was anticipated, and the Fund may lose money. Some Alternative Strategies may be considered speculative.

Commodity-related Investment Risk. The value of commodities investments will generally be affected by overall market movements and factors specific to a particular industry or commodity, which may include demand for the commodity, weather, embargoes, tariffs, and economic health, political, international, regulatory and other developments. Exposure to commodities and commodities markets may subject the value of the Fund’s investments to greater volatility than other types of investments. Commodities investments may also subject the Fund to counterparty risk and liquidity risk. The Fund may invest in one or more underlying funds that make commodity-related investments through one or more wholly-owned subsidiaries organized outside the U.S. that are generally not subject to U.S. laws (including securities laws) and their protections. The Fund's investments in commodities or commodity-related investments can be limited by the Fund's intention to qualify as a regulated investment company and can limit the Fund's ability to so qualify. If an underlying fund in which the Fund invests that itself invests directly or indirectly in commodities fails to qualify as a regulated investment company, such failure could also cause the Fund to fail to so qualify.

Confidential Information Access Risk. Portfolio managers may avoid the receipt of material, non-public information (Confidential Information) about the issuers of floating rate loans (including from the issuer itself) being considered for acquisition by the Fund, or held in the Fund. A decision not to receive Confidential Information may disadvantage the Fund and could adversely affect the Fund’s performance.

Convertible Securities Risk. Convertible securities are subject to the usual risks associated with debt instruments, such as interest rate risk and credit risk. Convertible securities also react to changes in the value of the common stock into which they convert, and are thus subject to market risk. The Fund may also be forced to convert a convertible security at an inopportune time, which may decrease the Fund’s return.

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.

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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. Rating agencies assign credit ratings to certain 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 Standard and Poor’s Ratings Services, or equivalently rated by Moody’s Investors Service, Inc. or Fitch, 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 Standard and Poor’s Ratings Services, or equivalently rated by Moody’s Investors Service, Inc. or Fitch, 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.

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, 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 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, leverage risk, liquidity risk, pricing risk and volatility risk.

Derivatives Risk – Structured Investments Risk. Structured investments are over-the-counter derivatives that provide principal and/or interest payments based on the value of an underlying reference(s). Structured investments typically provide interest income, thereby offering a potential yield advantage over investing directly in an underlying reference. Structured investments may lack a liquid secondary market and their prices or value can be volatile which could result in significant losses for the Fund. In some cases, depending on its terms, a structured investment may provide that principal and/or interest payments may be adjusted below zero resulting in a potential loss of principal and/or interest payments. Additionally, the particular terms of a structured investment may create economic leverage by

Columbia Diversified Real Return Fund

requiring payment by the issuer of an amount that is a multiple of the price change of the underlying reference. Economic leverage will increase the volatility of structured investment prices, and could result in increased losses for the Fund. The Fund’s use of structured instruments may not work as intended. If structured investments are used to reduce the duration of the Fund’s portfolio, this may limit the Fund’s return when having a longer duration would be beneficial (for instance, when interest rates decline). Structured investments 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, 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.

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries, and some have a higher risk of currency devaluations.

Exchange-Traded Fund (ETF) Risk. Investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs. ETFs are subject to, among other risks, tracking risk and passive and, in some cases, active investment risk. In addition, shareholders bear both their proportionate share of the Fund’s expenses, and indirectly the ETF’s expenses, incurred through the Fund’s ownership of the ETF. Because the expenses and costs of an underlying ETF are shared by its investors, redemptions by other investors in the ETF could result in decreased economies of scale and increased operating expenses for such ETF. The ETFs may not achieve their investment objective. The Fund, through its investment in ETFs, may not achieve its investment objective.

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 and terrorism), 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.

Fund-of-Funds Risk. Determinations regarding asset classes or underlying funds and the Fund’s allocations thereto may not successfully achieve the Fund’s investment objective, in whole or in part. The ability of the Fund to realize its investment objective will depend, in large part, on the extent to which the underlying funds realize their investment objective. There is no guarantee that the underlying funds will achieve their respective investment objectives. The Fund is exposed to the same risks as the underlying funds in direct proportion to the allocation of its assets among the underlying funds. Therefore, to the extent that the Fund invests significantly in a particular underlying fund, the Fund’s performance would be significantly impacted by the performance of such underlying fund. Generally, by

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investing in a combination of underlying funds, the Fund has exposure to the risks of many areas of the market. By concentrating its investments in relatively few underlying funds, the Fund may have more concentrated market exposures, subjecting the Fund to greater risk of loss should those markets decline or fail to rise. The performance of underlying funds could be adversely affected if other entities that invest in the same underlying funds make relatively large investments or redemptions in such underlying funds. The Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each underlying fund are shared by its investors, redemptions by other investors in an underlying fund could result in decreased economies of scale and increased operating expenses for such fund. The Investment Manager may have conflicts of interest in selecting affiliated funds (from which it receives management fees) over unaffiliated funds (from which it does not receive management fees) for investment by the Fund, and may also face conflicts of interest in selecting affiliated funds, because the fees the Investment Manager receives from some underlying funds may be higher than the fees paid by other underlying funds. Also, to the extent that the Fund is constrained/restricted from investing (or investing further) in a particular underlying fund for one or more reasons (e.g., underlying fund capacity constraints or regulatory restrictions) or if the Fund chooses to sell its investment in an underlying fund because of poor investment performance or for other reasons, the Fund may have to invest in another underlying fund(s), including less desirable funds – from a strategy or investment performance standpoint – which could have a negative impact on Fund performance. In addition, Fund performance could be negatively impacted if an appropriate alternate underlying fund(s) does not present itself in a timely manner or at all.

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.

Highly Leveraged Transactions Risk. The loans or other debt instruments in which the Fund invests may include highly leveraged transactions whereby the borrower assumes large amounts of debt in order to have the financial resources to attempt to achieve its business objectives. Loans or other debt instruments that are part of highly leveraged transactions involve a greater risk (including default and bankruptcy) than other investments.

Impairment of Collateral Risk. The value of collateral, if any, securing a loan can decline, and may be insufficient to meet the borrower’s obligations or difficult or costly to liquidate. In addition, the Fund’s access to collateral may be limited by bankruptcy or other insolvency laws. Further, certain floating rate and other loans may not be fully collateralized and may decline in value.

Inflation Risk. Inflation risk is the uncertainty over the future real value (after inflation) of an investment. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy, and the Fund’s investments may not keep pace with inflation, which may result in losses to Fund investors.

Inflation-Protected Securities Risk. Inflation-protected debt securities tend to react to changes in real interest rates (i.e., nominal interest rates minus the expected impact of inflation). In general, the price of such securities falls when real interest rates rise, and rises when real interest rates fall. Interest payments on these securities will vary and may be more volatile than interest paid on ordinary bonds. In periods of deflation, the Fund may have no income at all from such investments.

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. Similarly, a period of rising interest rates may negatively impact the Fund’s performance. 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

Columbia Diversified Real Return Fund

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, and the value of its loans or securities may therefore decline, which would negatively affect the Fund’s performance. Poor performance 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 or other events, conditions or factors. The market capitalization of an issuer may also impact its risk profile. Investments in larger, more established companies may involve certain risks associated with their larger size. For instance, larger, more established companies may be less able to respond quickly to new competitive challenges, such as changes in consumer tastes or innovation from smaller competitors. Also, larger companies are sometimes less able to attain the high growth rates of successful smaller companies, especially during extended periods of economic expansion.

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 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. 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. Floating rate loans generally are subject to legal or contractual restrictions on resale, may trade infrequently, their value may be impaired when the Fund needs to liquidate such loans, and are typically subject to extended settlement periods, each of which gives rise to liquidity risk.

Loan Assignment/Loan Participation Risk. If a bank loan is acquired through an assignment, the Fund may not be able to unilaterally enforce all rights and remedies under the loan and with regard to any associated collateral. If a bank loan is acquired through a participation, the Fund generally will have no right to enforce compliance by the borrower with the terms of the loan agreement, and the Fund may not benefit from the collateral supporting the debt obligation in which it has purchased the participation. As a result, the Fund will be exposed to the credit risk of both the borrower and the institution selling the participation.

Loan Interests Risk. Loan interests may not be considered “securities,” and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws. Loan interests generally are subject to restrictions on transfer, and the Fund may be unable to sell its loan interests at a time when it may otherwise be desirable to do so or may be able to sell them only at prices that are less than what the Fund regards as their fair market value. Accordingly, loan interests may at times be illiquid. Loan interests may be difficult to value and typically have extended settlement periods (generally greater than 7 days). Extended settlement periods during significant Fund redemption activity could potentially cause short-term liquidity demands within the Fund. In seeking to meet liquidity demands, the Fund could be forced to sell investments at unfavorable prices, or borrow money or effect short settlements when possible (at a cost to the Fund), in an effort to generate sufficient cash to pay redeeming shareholders. The Fund’s actions in this regard may not be successful. Interests in loans made to finance

7	Columbia Diversified Real Return Fund

highly leveraged companies or transactions, such as corporate acquisitions, may be especially vulnerable to adverse changes in economic or market conditions. Interests in secured loans have the benefit of collateral and, typically, of restrictive covenants limiting the ability of the borrower to further encumber its assets. There is a risk that the value of any collateral securing a loan in which the Fund has an interest may decline and that the collateral may not be sufficient to cover the amount owed on the loan. In the event the borrower defaults, the Fund’s access to the collateral may be limited or delayed by bankruptcy or other insolvency laws. 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, and the Fund, to enforce its rights in the event of a default, bankruptcy or similar situation, may need 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. In the event of a default, second lien secured loans will generally be paid only if the value of the collateral exceeds the amount of the borrower’s obligations to the first lien secured lenders, and the remaining collateral may not be sufficient to cover the full amount owed on the loan in which the Fund has an interest. The Fund may acquire a participation interest in a loan that is held by another party. When the Fund’s loan interest is a participation, the Fund may have less control over the exercise of remedies than the party selling the participation interest, and it normally would not have any direct rights against the borrower.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. In general, commodity investments tend to have greater price volatility than debt securities.

Money Market Fund Investment Risk. An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the FDIC or any other government agency. Certain money market funds float their NAV while others seek to preserve the value of investments at a stable NAV (typically, $1.00 per share). An investment in a money market fund, even an investment in a fund seeking to maintain a stable NAV per share, is not guaranteed and it is possible for the Fund to lose money by investing in these and other types of money market funds. If the liquidity of a money market fund’s portfolio deteriorates below certain levels, the money market fund may suspend redemptions (i.e., impose a redemption gate) and thereby prevent the Fund from selling its investment in the money market fund or impose a fee of up to 2% on amounts the Fund redeems from the money market fund (i.e., impose a liquidity fee). These measures may result in an investment loss or prohibit the Fund from redeeming shares when the Investment Manager would otherwise redeem shares. In addition to the fees and expenses that the Fund directly bears, the Fund indirectly bears the fees and expenses of any money market funds in which it invests, including affiliated money market funds. By investing in a money market fund, the Fund will be exposed to the investment risks of the money market fund in direct proportion to such investment. To the extent the Fund invests in instruments such as derivatives, the Fund may hold investments, which may be significant, in money market fund shares to cover its obligations resulting from the Fund’s investments in derivatives. Money market funds and the securities they invest in are subject to comprehensive regulations. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operation, performance and/or yield of money market funds.

Preferred Stock Risk. Preferred stock is a type of stock that generally pays dividends at a specified rate and that has preference over common stock in the payment of dividends and the liquidation of assets. Preferred stock does not ordinarily carry voting rights. The price of a preferred stock is generally determined by earnings, type of products or services, projected growth rates, experience of management, liquidity, and general market conditions of the markets on which the stock trades. The most significant risks associated with investments in preferred stock include issuer risk, market risk and interest rate risk (i.e., the risk of losses attributable 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 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 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.

Real Estate-Related Investment Risk. Investments in real estate investment trusts (REITs) and in securities of other companies (wherever organized) principally engaged in the real estate industry subject the Fund to, among other things, risks similar to those of direct investments in real estate and the real estate industry in general. These

Columbia Diversified Real Return Fund

include risks related to general and local economic conditions, possible lack of availability of financing and changes in interest rates or property values. REITs are entities that either own properties or make construction or mortgage loans, and also may include operating or finance companies. The value of interests in a REIT may be affected by, among other factors, changes in the value of the underlying properties owned by the REIT, changes in the prospect for earnings and/or cash flow growth of the REIT itself, defaults by borrowers or tenants, market saturation, decreases in market rates for rents, and other economic, political, or regulatory matters affecting the real estate industry, including REITs. REITs and similar non-U.S. entities depend upon specialized management skills, may have limited financial resources, may have less trading volume in their securities, and may be subject to more abrupt or erratic price movements than the overall securities markets. REITs are also subject to the risk of failing to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended. The failure of a REIT to continue to qualify as a REIT for tax purposes can materially and adversely affect its value. In addition, due to recent changes in tax laws, certain tax benefits of REITs may not be passed through to mutual fund shareholders. Some REITs (especially mortgage REITs) are affected by risks similar to those associated with investments in debt securities including changes in interest rates and the quality of credit extended.

Regulatory Risk — Alternative Investments. Legal, tax, and regulatory developments may adversely affect the Fund and its investments. The regulatory environment for the Fund and certain of its investments is evolving, and changes in the regulation of investment funds, their managers, and their trading activities and capital markets, or a regulator’s disagreement with the Fund’s or others’ interpretation of the application of certain regulations, may adversely affect the ability of the Fund to pursue its investment strategy, its ability to obtain leverage and financing, and the value of investments held by the Fund. There has been an increase in governmental, as well as self-regulatory, scrutiny of the investment industry in general and the alternative investment industry in particular. It is impossible to predict what, if any, changes in regulations may occur, but any regulation that restricts the ability of the Fund or any underlying funds or other investments to trade in securities or other instruments or the ability of the Fund or underlying funds to employ, or brokers and other counterparties to extend, credit in their trading (as well as other regulatory changes that result) could have a material adverse impact on the Fund’s performance.

Reinvestment Risk. Reinvestment risk is the risk that the Fund will not be able to reinvest income or principal at 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 liquidity and other 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 may invest in private placements determined to be liquid as well as those determined to be illiquid. Even if determined to be liquid, 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 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.

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

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. Sovereign debt risk is increased for emerging market issuers.

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.

9	Columbia Diversified Real Return 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 blended benchmark that is intended to provide a measure of the Fund's performance given its investment strategy, as well as another measure of performance for markets in which the Fund may invest.

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 (without applicable sales charges and adjusted to reflect the higher class-related operating expenses of such classes, where applicable) 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. Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

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	_{2nd Quarter 2016}	_5.65%
	_Worst	_{3rd Quarter 2015}	_-4.41%

*	Year to Date return as of March 31, 2018: 1.07%

Columbia Diversified Real Return Fund

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2017)

	Share Class Inception Date	1 Year	Life of Fund
Class A	03/11/2014
returns before taxes		-1.83%	-0.02%
returns after taxes on distributions		-2.91%	-1.12%
returns after taxes on distributions and sale of Fund shares		-1.04%	-0.52%
Class Adv returns before taxes	03/11/2014	3.30%	1.52%
Class C returns before taxes	03/11/2014	1.27%	0.51%
Class Inst returns before taxes	03/11/2014	3.30%	1.53%
Class Inst2 returns before taxes	03/11/2014	3.26%	1.48%
Class Inst3 returns before taxes	03/01/2017	3.26%	1.32%
Class T returns before taxes	06/25/2014	0.50%	0.57%
Blended Benchmark (consisting of 35% Bloomberg Barclays Global Inflation-Linked Index (Hedged), 30% Credit Suisse Leveraged Loan Index, 20% Bloomberg Barclays U.S. Dollar Floating Rate Note (FRN) Index and 15% Bloomberg Commodity Index Total Return) (reflects no deductions for fees, expenses or taxes)		3.14%	1.69%
FTSE Three-Month U.S. Treasury Bill Index (reflects no deductions for fees, expenses or taxes)		0.84%	0.31%

Fund Management

Investment Manager: Columbia Management Investment Advisers, LLC

Portfolio Manager	Title	Role with Fund	Managed Fund Since
Anwiti Bahuguna, Ph.D.	Senior Portfolio Manager	Lead Portfolio Manager	2017
Dan Boncarosky, CFA	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 Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		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 & T^(a)	All accounts other than IRAs	$2,000	$100
Classes A, C & T^(a)	IRAs	$1,000	$100
Classes Adv & 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)

(a)	Class T shares must be purchased through financial intermediaries that, by written agreement with Columbia Management Investment Distributors, Inc., are specifically authorized to sell Class T shares.

11	Columbia Diversified Real Return Fund

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. The use of a fund-of-funds structure could affect the timing, amount and character of distributions to you and therefore may increase the amount of taxes payable by you. 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 Diversified Real Return Fund

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

columbiathreadneedleus.com

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