SmartStop Self Storage REIT, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31,2025

OR

For the transition period from to

Commission File Number:001-42584

(Exact name of Registrant as specified in its charter)

10 Terrace Rd.

Ladera Ranch, California 92694

(Address of principal executive offices)

(866)418-5144

(Registrant’s telephone number)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

Common Stock, Class A, and Class T, $0.001 par value per share

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐No ☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically, every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definitions of “large accelerated filer”, “accelerated filer”, “smaller reporting company”, and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No☒

The aggregate market value of the common stock held by non-affiliates of the registrant was $2,000,553,000 based upon the closing price on the New York Stock Exchange on June 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter.

As of February 18, 2026, there were 55,357,177 shares outstanding of the registrant’s common stock.

Documents Incorporated by Reference: The registrant incorporates by reference in Part III (Items 10, 11, 12, 13 and 14) of this Form 10-K portions of its Definitive Proxy Statement for the 2026 Annual Meeting of Stockholders. The registrant’s Definitive Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.

TABLE OF CONTENTS

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Certain statements contained in this report, other than historical facts, may be considered forward-looking statements within the meaning of the federal securities laws, and we intend for all such forward-looking statements to be covered by the applicable safe harbor provisions for forward-looking statements contained in such federal securities laws. Such forward-looking statements can generally be identified by our use of forward-looking terminology such as “may,” “will,” “expect,” “intend,” “anticipate,” “estimate,” “believe,” “seek,” “continue,” or other similar words, or the negative of such terms or other comparable terminology, or by discussions of strategy. We may also make additional forward-looking statements from time to time. All such subsequent forward-looking statements, whether written or oral, by us or on our behalf, are also expressly qualified by these cautionary statements.

Such statements include, but are not limited to statements concerning our plans, strategies, initiatives, prospects, objectives, goals, future events, future revenues or performance, capital expenditures, financing needs, plans or intentions relating to acquisitions and other information that is not historical information. Such statements are subject to known and unknown risks and uncertainties, which could cause actual results to differ materially from those projected or anticipated, including, without limitation:

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disruptions in the economy, including debt and banking markets and foreign currency, including changes in the Canadian Dollar (“CAD”)/U.S. Dollar (“USD”) exchange rate;

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significant transaction costs, including financing costs, and unknown liabilities;

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whether we will be successful in the pursuit of our business plan and investment objectives;

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changes in the political and economic climate, economic conditions and fiscal imbalances in the United States, and other major developments, including tariffs, wars, natural disasters, epidemics and pandemics, military actions, and terrorist attacks;

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changes in tax and other laws and regulations, including tenant protection programs and other aspects of our business;

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difficulties in our ability to attract and retain qualified personnel and management;

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the effect of competition at our self-storage properties or from other storage alternatives, which could cause rents and occupancy rates to decline;

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our ability to identify and complete acquisitions on favorable terms or at all;

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our ability to successfully integrate businesses and opportunities that we acquire, including but not limited to, the potential failure to fully realize expected cost savings and synergies from transactions or the risk that those expected cost savings and synergies may take longer than anticipated to be realized;

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the outcome of any pending or later instituted legal or regulatory proceedings or governmental inquiries or investigations;

•

general competitive, economic, political and market conditions and other factors that may affect our future results;

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our reliance on information technologies, which are vulnerable to, among other things, attack from computer viruses and malware, hacking, cyberattacks and other unauthorized access or misuse;

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increases in interest rates; and

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failure to maintain our REIT status.

All forward-looking statements, including without limitation, management’s examination of historical operating trends and estimates of future earnings, are based upon our current expectations and various assumptions. Our expectations, beliefs and projections are expressed in good faith, and we believe there is a reasonable basis for them, but there can be no assurance that management’s expectations, beliefs and projections will result or be achieved. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date this report is filed with the Securities and Exchange Commission (the “SEC”) and are not intended to be a guarantee of our performance in future periods. We cannot guarantee the accuracy of any such forward-looking statements contained in this report, and we do not intend to publicly update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise.

For further information regarding risks and uncertainties associated with our business, and important factors that could cause our actual results to vary materially from those expressed or implied in such forward-looking statements, please refer to the factors listed and described under “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the “Risk Factors” sections of the documents we file from time to time with the SEC, including, but not limited to, this report, copies of which may be obtained from our website atinvestors.smartstopselfstorage.com.