X0508 4 2023-11-09 0 0001549922 Summit Midstream Partners, LP SMLP 0001823482 Johnston James David C/O SUMMIT MIDSTREAM PARTNERS, LP 910 LOUISIANA STREET, SUITE 4200 HOUSTON TX 77002 0 1 0 0 See remarks below. 1 Common Units 2023-11-09 4 S 0 1995 20.19 D 27381 D Common Units 2023-11-10 4 S 0 531 20.47 D 26850 D These units were sold in compliance with a qualified selling plan adopted by the reporting person pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. The price reported in Column 4 is a weighted average price and has been rounded to the nearest cent. These units were sold in multiple transactions at prices ranging from $20.05 to $20.60, inclusive. The reporting person undertakes to provide to Summit Midstream Partners, LP, any security holder of Summit Midstream Partners, LP, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of units sold at each separate price within the ranges set forth in footnote 2 to this Form 4. The price reported in Column 4 is a weighted average price and has been rounded to the nearest cent. These units were sold in multiple transactions at prices ranging from $20.05 to $20.72, inclusive. The reporting person undertakes to provide to Summit Midstream Partners, LP, any security holder of Summit Midstream Partners, LP, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of units sold at each separate price within the ranges set forth in footnote 3 to this Form 4. The Reporting Person is Executive Vice President, General Counsel, and Chief Compliance Officer of Summit Midstream GP, LLC, the general partner of the Issuer (the "General Partner"). The Issuer is managed by the directors and executive officers of the General Partner. /s/ James D. Johnston 2023-11-14