Summit Midstream Corp

During the three months ended March 31, 2026, the following officer (as defined in Rule 16a-1(f) under the Exchange Act) of the Company adopted a Rule 10b5-1 trading arrangement as defined in Item 408(a) of Regulation S-K.

James D. Johnston, the Company’s Executive Vice President, General Counsel and Chief Compliance Officer, entered into a Rule 10b5-1 trading arrangement adopted March 23, 2026 (the “Adoption Date”) providing for the sale from time to time of an aggregate of up to 10,400 shares of our common stock subject to limit price, no-sale periods, monthly quantity limits, and a selling start date the later of (i) July 2, 2026, (ii) the 91st day after the Adoption Date, or the earlier of (iii) the third business day following issuance of the financial results in this Form 10-Q or the 121 st day after the Adoption Date. No transactions have occurred under the trading arrangement. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is until April 5, 2027, or earlier expiration if all transactions under the trading arrangement are completed.