144 0001649051 XXXXXXXX LIVE 0001845257 LIFESTANCE HEALTH GROUP, INC. 001-40478 4800 N. SCOTTSDALE ROAD SUITE 2500 SCOTTSDALE AZ 85251 602-7672100 Silversmith Capital Partners I-B, L.P. Shareholder Common Stock Morgan Stanley & Co. LLC

1585 Broadway New York NY 10036

894098 4837070.18 388936394 08/18/2025 NASDAQ Common Stock 06/10/2021 Pre-IPO Transactions Issuer N 5130460 06/10/2021 Equity interests in the Issuer were purchased pre-IPO Y Sales by Seller should be aggregated with the sale of common stock by Summit Partners Growth Equity Fund IX-A, L.P., Summit Partners Growth Equity Fund IX-B, L.P., Summit Investors GE IX-VC IV, LLC, Summit Investors GE IX-VC IV (UK), L.P., Summit Partners Entrepreneur Advisors II, L.P., Silversmith Capital Partners I-A, L.P., and Silversmith Capital Partners I-C, L.P. (together with Seller, the "Selling Shareholders"). The Selling Shareholders have filed separate Forms 144 for aggregate sales of 12,000,000 shares of common stock during the past three months. 08/18/2025 /s/ Jeff Crisan