X0306 4 2021-06-14 0 0001845257 LifeStance Health Group, Inc. LFST 0000830588 SUMMIT PARTNERS L P 222 BERKELEY STREET 18TH FLOOR BOSTON MA 02116 0 0 0 1 Manager of GP of 10% owner 0001627278 SUMMIT MASTER COMPANY, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 0 1 Manager of Manager of 10% owne 0001846778 SUMMIT PARTNERS ENTREPRENEUR ADVISORS GP II, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 0 1 GP of 10% owner 0001846731 SUMMIT PARTNERS GE IX, L.P. 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 0 1 GP of 10% owner 0001846688 SUMMIT PARTNERS GE IX, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 0 1 GP of 10% owner 0001507545 Summit Investors Management, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 0 1 Manager and GP of 10% Owner Common Stock 2021-06-14 4 S 0 1368844 17.01 D 46875407 I See Footnotes. Represents 838,224 shares sold by Summit Partners Growth Equity Fund IX-A, L.P., 523,375 shares sold by Summit Partners Growth Equity Fund IX-B, L.P., 5,851 shares sold by Summit Investors GE IX/VC IV, LLC, 782 shares sold by Summit Partners Entrepreneur Advisors Fund II, L.P., and 612 shares sold by Summit Investors GE IX/VC IV (UK), L.P. Represents 28,704,562 shares held by Summit Partners Growth Equity Fund IX-A, L.P., 17,922,731shares held by Summit Partners Growth Equity Fund IX-B, L.P., 200,368 shares held by Summit Investors GE IX/VC IV, LLC, 26,786 shares held by Summit Partners Entrepreneur Advisors Fund II, L.P., and 20,960 shares held by Summit Investors GE IX/VC IV (UK), L.P. Summit Partners, L.P. is the managing member of Summit Partners GE IX, LLC, which is general partner of Summit Partners GE IX, LP, which is the general partner of Summit Partners Growth Equity Fund IX-A, L.P. and Summit Partners Growth Equity Fund IX-B, L.P. Summit Master Company, LLC is (i) the sole member of Summit Partners Entrepreneur Advisors GP II, LLC, which is the general partner of Summit Partners Entrepreneur Advisors Fund II, L.P. and (ii) the general partner of Summit Partners L.P., which is the manager of Summit Investors Management, LLC, which is the manager of Summit Investors GE IX/VC IV, LLC, and the general partner of Summit Investors GE IX/VC IV (UK), L.P. Summit Master Company, LLC, as the sole member of Summit Partners Entrepreneur Advisors GP II, LLC and the managing member of Summit Investors Management, LLC, has delegated investment decisions, including voting and dispositive power, to Summit Partners, L.P. and its investment committee responsible for voting and investment decisions with respect to LifeStance Health Group, Inc. Summit Partners, L.P., through a three-person investment committee, currently composed of Peter Y. Chung, Mark A. deLaar and Craig D. Frances, has voting and dispositive authority over the shares held by each of these entities and therefore beneficially owns such shares. Each of the Summit Funds, Mr. Chung, Mr. deLaar and Dr. Frances disclaim disclaims beneficial ownership of the shares, except, in each case, to the extent of such person's or entity's pecuniary interest therein. Summit Partners, L.P., by Summit Master Company, LLC, its GP, by /s/ Robin W. Devereux, Member 2021-06-16 Summit Master Company, LLC, by Robin W. Devereux, Member 2021-06-16 Summit Partners Entrepreneur Advisors GP II, LLC, by Summit Master Company, its Sole Member, by Robin W. Devereux, Member 2021-06-16 Summit Partners GE IX, L.P., by Summit Partners GE IX, LLC, its General Partner, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by /s/ Robin W. Devereux, Member 2021-06-16 Summit Partners GE IX, LLC, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by /s/ Robin W. Devereux, Member 2021-06-16 Summit Investors Management, LLC, by Summit Master Company, LLC, its Managing Member, by Robin W. Devereux, Member 2021-06-16