X0609 4 2026-07-16 0001661998 Q32 Bio Inc. QTTB 0001618273 Kalowski Lee false Q32 BIO INC. 830 WINTER STREET WALTHAM MA 02451 false true false false CFO and President false Common Stock 2026-07-16 4 A false 53250 0 A 142443 D Represents shares of Issuer common stock underlying performance-based restricted stock units ("PSUs") granted on July 6, 2026, which vested on July 16, 2026 with respect to a performance-based condition, upon achievement of the closing of a financing of at least $100,000,000 in gross proceeds on or before December 31, 2026. Such PSUs are also subject to a time-based condition, which provides that the PSUs shall vest in equal quarterly installments over three years from July 1, 2026, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. Each PSU represents a contingent right to receive one share of Issuer common stock. /s/ Eric Bell, Attorney-in-Fact 2026-07-20