SmartStop Self Storage REIT, Inc.

For the year ended December 31, 2025, there was no information required to be disclosed in a report on Form 8-K which was not disclosed in a report on Form 8-K.

During the three months ended December 31, 2025, David Mueller, one of ourdirectors, adopted a trading arrangement intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. This trading arrangement was adopted on December 15, 2025, pursuant to which Mr. Mueller intends to sell 425 shares of our Common Stock on or about the 16th of each month beginning on March 16, 2026 and ending on February 16, 2027. The transactions that occur under the trading arrangement, if any, will be subject to the terms and conditions set forth therein. Other than Mr. Mueller, none of our directors or officers (as defined in Rule 16a-1(f) of the Exchange Act)adopted, terminated, ormodifiedany contract, instruction or written plan for the purchase or sale of our securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any non-Rule 10b5-1 trading arrangement (as defined in Item 408 of Regulation S-K).