144 0001977613 XXXXXXXX LIVE 0001845257 LifeStance Health Group, Inc. 001-40478 4800 N. Scottsdale Road Suite 2500 Scottsdale AZ 85251 602-767-2100 TPG VIII Lynnwood Holdings Aggregation, L.P. Stockholder Common Stock, par value $0.01 per share Citadel Securities, LLC

830 Brickell Plaza Miami FL 33131

13643207 147892363.88 382055609 08/10/2026 NASDAQGS Common Stock, par value $0.01 per share 06/09/2021 The shares of Common Stock reported herein were originally acquired by Seller from Issuer in a reorganization that preceded its initial public offering. Issuer N 184902826 06/09/2021 Contribution of limited partner interests for shares of Common Stock Y Sales by Seller should be aggregated with the sales of shares of Common Stock of the Issuer 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 Partners Entrepreneur Advisors Fund II, L.P. and Summit Investors GE IX/VC IV (UK), L.P. (together with Seller, the "Selling Stockholders"). The Selling Stockholders have filed separate Forms 144 for aggregate sales of 16,489,203 shares of Common Stock of the Issuer during the past three months. 08/10/2026 /s/ Matthew White