X0609 4 2026-10-06 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 2026-10-06 4 S false 1301 8.3198 D 137170 D Represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of performance-based restricted stock units. These sales were automatic and not in the discretion of the Reporting Person. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $8.08 to $8.32. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, on request, full information regarding the number of shares sold at each separate price within the range set forth above. /s/ Eric Bell, Attorney-in-Fact 2026-10-14