497 1 d39934d497.htm COLUMBIA ACORN TRUST COLUMBIA ACORN TRUST
Supplement dated July 2, 2025
to the Statement of Additional Information (SAI) of the following funds: 
Fund
SAI Dated
Columbia Acorn Trust
 Columbia Acorn European Fund
5/1/2025
 Columbia Acorn Fund
5/1/2025
 Columbia Acorn International
5/1/2025
 Columbia Acorn International Select
5/1/2025
 Columbia Thermostat Fund
5/1/2025
On June 26, 2025, the Funds’ Board of Trustees approved a Novation of Management Agreement pursuant to which all rights, duties and obligations under the Funds’ current Management Agreement with Columbia Wanger Asset Management, LLC (CWAM) will transfer to its parent company Columbia Management Investment Advisers, LLC (Columbia Management) on or about July 7, 2025 (the Effective Date). Columbia Management is currently the sub-administrator of the Funds and is the investment adviser of each of the other Columbia Funds. The services provided to, and management fees paid by, the Funds will not change as a result of this transfer and the current portfolio managers of the Funds will continue to manage the Funds after the transition.
As of the Effective Date, all references in the SAI to CWAM as the Investment Manager and the Administrator of the Funds, other than references to CWAM with respect to fees or other payments received by CWAM for advisory and administrative services for periods prior to July 7, 2025, are replaced with Columbia Management as the Investment Manager and the Administrator of the Funds, and all references to Columbia Management as Sub-Administrator are deleted. In addition, the following changes are hereby made to the SAI.
The disclosure under the heading “Investment Management and Other Services – The Investment Manager” section of the SAI is hereby superseded and replaced with the following:
Columbia Management Investment Advisers, LLC is located at 290 Congress Street, Boston, MA 02210 and serves as investment adviser and administrator to the Columbia Funds. The Investment Manager is a registered investment adviser and a wholly-owned subsidiary of Ameriprise Financial. The Investment Manager’s management experience covers all major asset classes, including equity securities, debt instruments and money market instruments. In addition to serving as an investment adviser to traditional mutual funds, exchange-traded funds and closed-end funds, the Investment Manager acts as an investment adviser for itself, its affiliates, individuals, corporations, retirement plans, private investment companies and financial intermediaries.
The Investment Manager and its investment advisory affiliates (Participating Affiliates) around the world may coordinate in providing services to their clients. Such coordination may include functional leadership of the business (the “global” business). From time to time, the Investment Manager may engage its Participating Affiliates to provide a variety of services such as investment research, investment monitoring, trading, and discretionary investment management (including portfolio management and proxy voting) to certain accounts managed by the Investment Manager, including the funds. These Participating Affiliates will provide services to the funds and other accounts of the Investment Manager either pursuant to delegation agreements, personnel-sharing agreements or similar inter-company or other arrangements or relationships and the funds will pay no additional fees and expenses as a result of any such arrangements or relationships. These Participating Affiliates, like the Investment Manager, are direct or indirect subsidiaries of Ameriprise Financial and are registered with the appropriate respective regulators in their home jurisdictions and, where required, the SEC and the CFTC in the United States.
Pursuant to some of these arrangements or relationships, certain personnel of these Participating Affiliates serve as “associated persons” or officers of the Investment Manager and, in this capacity, subject to the oversight and supervision of the Investment Manager and consistent with the investment objectives, policies and limitations set forth in the Funds' prospectuses and this SAI, and with the Investment Manager’s and the Funds' compliance policies and procedures, provide services to the funds.
As a manager of global equities, fixed income and real estate assets, Columbia Management seeks to provide its investment professionals, including Fund portfolio managers, with access to various internal tools and resources that they may use to enhance or supplement their investment processes, including access to Columbia Management’s proprietary Fundamental Research capability, Quantitative Equity Research capability, and Responsible Investing Research capability, each as further described below.
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Columbia Management’s Equity and Fixed Income Fundamental Research Capability
Columbia Management and its advisory affiliates maintain an internal central research function for both equity and fixed income. Investment analysts who are responsible for central research provide their views on specific issuers and securities internally for general consumption by other analysts and portfolio managers, as well as to investment personnel of certain of our advisory affiliates. Fund portfolio managers may, by way of example, seek to leverage the central fundamental research for sector expertise. Equity analysts that are tied to specific portfolio management teams or strategies generally do not provide their research internally in this manner but may share their investment views with investment personnel (including personnel at certain of our advisory affiliates) via email or other form of communication. In addition, certain of our research analysts have portfolio management responsibilities that may create potential conflicts of interest with respect to the allocation of investment research. We have adopted policies and related controls to manage these conflicts.
Columbia Management’s Quantitative Equity Research Capability
Columbia Management’s quantitative research team applies fundamental investment concepts within a quantitative and systematic framework to create robust sector- and industry-specific multi-factor stock selection models across three broad categories, including valuation (such as cash flow yield), catalyst (such as price momentum) and quality (such as earnings quality) models, to rank the securities within a sector/industry. A company’s rating is scaled from 1 (most attractive) to 5 (least attractive) based on the relative ranking of its overall score from its multi-factor model. The ranking results are another available resource internally for general consumption by other analysts and Fund portfolio managers, as well as to investment personnel of certain of our advisory affiliates. Fund portfolio managers may, by way of example, seek to leverage this information for the Funds they manage.
Columbia Management’s Responsible Investing Research Capability
Columbia Management maintains an internal central Responsible Investment (RI) research function. Columbia Management became a signatory to the United Nations-supported Principles for Responsible Investment (PRI) in October 2014. The PRI initiative is based on six principles that address the integration of environmental, social and governance (ESG) factors into investment decision-making and stewardship practices. As a PRI signatory, Columbia Management has made a commitment by investing in the resources, enhanced analytics and data to supplement its standard fundamental and quantitative tools to help its investment teams expand their investment mosaic to potentially consider and integrate ESG factors that seek to identify material associated risks and opportunities that may bear on the long-term value creation and sustainability of a company. While Columbia Management follows the PRI Principles, becoming a PRI signatory does not require the application of specific RI factors in Columbia Management’s investment process, and Columbia Management may take actions inconsistent with the PRI if, in its judgment, it is in the best interests of its clients to do so.
While Columbia Management believes that evaluating RI research and analysis enables portfolio managers to make better-informed investment decisions, each portfolio management team within Columbia Management makes its own investment decisions and certain teams may place more, less or no emphasis on ESG factors in any given investment decision. Columbia Management believes in being a responsible steward of the capital entrusted to it by our clients. Consistent with this philosophy and the duty to act in the best interests of our clients, our publicly available Stewardship Principles form an important part of our investment framework and guidelines. These Principles outline the governance of Columbia Management’s stewardship activities as they apply across asset classes, as well as specifying Columbia Management’s approach to monitoring the companies in which it invests and the role within stewardship of engagement and proxy voting.
The disclosure under the heading “Investment Management and Other Services – Management Agreement” section of the SAI is hereby superseded and replaced with the following:
Management Agreement
Pursuant to a Novation of Management Agreement effective on or about July 7, 2025, Columbia Management replaced CWAM, a wholly owned subsidiary of Columbia Management, as a party to the Management Agreement.
Prior to April 1, 2025, the Trust, on behalf of the Funds, was party to an investment advisory agreement (Advisory Agreement) and an administrative services agreement (Administration Agreement) with CWAM for advisory and administrative services, respectively. Each Fund paid CWAM an annual fee for advisory services, as set forth in the Advisory Agreement, and a separate fee for administrative services under the Administration Agreement. See “Investment Management and Other Services—The Administrator” for information with respect to the Administration Agreement. As of April 1, 2025, these services have been combined under the Management Agreement as described above.
See “Advisory Fees Paid by the Funds" and “Administration Fees Paid by the Funds" in this SAI for information on payments received by Columbia Management and by CWAM, Investment Manager and Administrator of the Funds prior to July 7, 2025.
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The disclosure under the heading “Investment Management and Other Services - The Portfolio Managers and Potential Conflicts of Interests” section of the SAI is hereby superseded and replaced with the following:
 
Columbia Management: Like other investment professionals with multiple clients, a Fund’s portfolio manager(s) may face certain potential conflicts of interest in connection with managing both the Fund and other accounts at the same time. The Investment Manager and the Funds have adopted compliance policies and procedures that attempt to address certain of the potential conflicts that portfolio managers face in this regard. Certain of these conflicts of interest are summarized below.
The management of funds or other accounts with different advisory fee rates and/or fee structures, including accounts, such as the Investment Manager’s hedge funds, that pay advisory fees based on account performance (performance fee accounts), may raise potential conflicts of interest for a portfolio manager by creating an incentive to favor accounts that pay higher fees, including performance fee accounts, such that the portfolio manager may have an incentive to allocate attractive investments disproportionately to performance fee accounts.
Similar conflicts of interest also may arise when a portfolio manager has personal investments in other accounts that may create an incentive to favor those accounts. When the Investment Manager determines it necessary or appropriate in order to ensure compliance with restrictions on joint transactions under the 1940 Act, a Fund may not be able to invest in privately-placed securities in which other accounts advised by the Investment Manager using a similar style, including performance fee accounts, are able to invest, even when the Investment Manager believes such securities would otherwise represent attractive investment opportunities. As a general matter and subject to the Investment Manager’s Code of Ethics and certain limited exceptions, including for investments in the Investment Manager’s hedge funds, the Investment Manager’s investment professionals do not have the opportunity to invest in client accounts, other than the Funds.
A portfolio manager who is responsible for managing multiple funds and/or accounts may devote unequal time and attention to the management of those Funds and/or accounts. The effects of this potential conflict may be more pronounced where Funds and/or accounts managed by a particular portfolio manager have different investment strategies.
A portfolio manager may be able to select or influence the selection of the broker/dealers that are used to execute securities transactions for the Funds. A portfolio manager’s decision as to the selection of broker/dealers could produce disproportionate costs and benefits among the Funds and the other accounts the portfolio manager manages.
A potential conflict of interest may arise when a portfolio manager buys or sells the same securities for a Fund and other accounts. On occasions when a portfolio manager considers the purchase or sale of a security to be in the best interests of a Fund as well as other accounts, the Investment Manager’s trading desk may, to the extent consistent with applicable laws and regulations, aggregate the securities to be sold or bought in order to obtain the best execution and lower brokerage commissions, if any. Aggregation of trades may create the potential for unfairness to a Fund or another account if a portfolio manager favors one account over another in allocating the securities bought or sold. The Investment Manager and its Participating Affiliates may coordinate their trading operations for certain types of securities and transactions pursuant to personnel-sharing agreements or similar intercompany arrangements. However, typically the Investment Manager does not coordinate trading activities with a Participating Affiliate with respect to accounts of that Participating Affiliate unless such Participating Affiliate is also providing trading services for accounts managed by the Investment Manager. Similarly, a Participating Affiliate typically does not coordinate trading activities with the Investment Manager with respect to accounts of the Investment Manager unless the Investment Manager is also providing trading services for accounts managed by such Participating Affiliate. As a result, it is possible that the Investment Manager and its Participating Affiliates may trade in the same instruments at the same time, in the same or opposite direction or in different sequence, which could negatively impact the prices paid by the Fund on such instruments. Additionally, in circumstances where trading services are being provided on a coordinated basis for the Investment Manager’s accounts (including the Funds) and the accounts of one or more Participating Affiliates in accordance with applicable law, it is possible that the allocation opportunities available to the Funds may be decreased, especially for less actively traded securities, or orders may take longer to execute, which may negatively impact Fund performance.
“Cross trades,” in which a portfolio manager sells a particular security held by a Fund to another account (potentially saving transaction costs for both accounts), could involve a potential conflict of interest if, for example, a portfolio manager is permitted to sell a security from one account to another account at a higher price than an independent third party would pay. The Investment Manager and the Funds have adopted compliance procedures that provide that any transactions between a Fund and another account managed by the Investment Manager are to be made at a current market price, consistent with applicable laws and regulations.
Another potential conflict of interest may arise based on the different investment objectives and strategies of a Fund and other accounts managed by its portfolio manager(s). Depending on another account’s objectives and other factors, a portfolio manager may give advice to and make decisions for a Fund that may differ from advice given, or the timing or nature of decisions made, with respect to another account. A portfolio manager’s investment decisions are the product of
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many factors in addition to basic suitability for the particular account involved. Thus, a portfolio manager may buy or sell a particular security for certain accounts, and not for a Fund, even though it could have been bought or sold for the Fund at the same time. A portfolio manager also may buy a particular security for one or more accounts when one or more other accounts are selling the security (including short sales). There may be circumstances when a portfolio manager’s purchases or sales of portfolio securities for one or more accounts may have an adverse effect on other accounts, including the Funds.
To the extent a Fund invests in underlying funds, a portfolio manager will be subject to the potential conflicts of interest described in Potential Conflicts of Interest – Columbia Management – FOF (Fund-of-Funds) below.
A Fund’s portfolio manager(s) also may have other potential conflicts of interest in managing the Fund, and the description above is not a complete description of every conflict that could exist in managing the Fund and other accounts. Many of the potential conflicts of interest to which the Investment Manager’s portfolio managers are subject are essentially the same or similar to the potential conflicts of interest related to the investment management activities of the Investment Manager and its affiliates.
In addition, a portfolio manager’s responsibilities may include working as a securities analyst. This dual role may give rise to conflicts with respect to making investment decisions for accounts that he/she manages versus communicating his/her analyses to other portfolio managers concerning securities that he/she follows as an analyst.
 
Columbia Management – FoF (Fund-of-Funds): Management of funds-of-funds differs from that of the other Funds. The portfolio management process is set forth generally below and in more detail in the Funds’ prospectus.
Portfolio managers of the fund-of-funds may be involved in determining each funds-of-fund’s allocation among the three main asset classes (equity, fixed income and cash) and the allocation among investment categories within each asset class, as well as each funds-of-fund’s allocation among the underlying funds.
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Because of the structure of the funds-of-funds, the potential conflicts of interest for the portfolio managers may be different than the potential conflicts of interest for portfolio managers who manage other Funds.
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The Investment Manager and its affiliates may receive higher compensation as a result of allocations to underlying funds with higher fees.
In addition to the accounts above, portfolio managers may manage accounts in a personal capacity that may include holdings that are similar to, or the same as, those of the Fund. The Investment Manager has in place a Code of Ethics that is designed to address conflicts and that, among other things, imposes restrictions on the ability of the portfolio managers and other “investment access persons” to invest in securities that may be recommended or traded in the Fund and other client accounts.
To the extent a fund-of-funds invest in securities and instruments other than other Funds, the portfolio manager is subject to the potential conflicts of interest described in Potential Conflicts of Interest – Columbia Management above.
A Fund’s portfolio manager(s) also may have other potential conflicts of interest in managing the Fund, and the description above is not a complete description of every conflict that could exist in managing the fund and other accounts. Many of the potential conflicts of interest to which the Investment Manager’s portfolio managers are subject are essentially the same or similar to the potential conflicts of interest related to the Investment Management activities of the Investment Manager and its affiliates.
Effective immediately, the fourth and fifth sentences under the subsection, “The Transfer Agent,” in the “Investment Management and Other Services - Other Services Providers” section of the SAI is hereby superseded and replaced with the following:
The Transfer Agent retains SS&C GIDS, Inc., 30 Braintree Hill Office Park, Suite 400, Braintree, MA 02184, as the Funds’ sub-transfer agent. SS&C GIDS, Inc. assists the Transfer Agent in carrying out its duties.
The rest of the section remains the same.
Shareholders should retain this Supplement for future reference.
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