X0306 4 2020-01-02 false 0001690585 Magenta Therapeutics, Inc. MGTA 0001741287 DAVIS JOHN C. JR C/O MAGENTA THERAPEUTICS, INC. 100 TECHNOLOGY SQUARE CAMBRIDGE MA 02139 false true false false Chief Medical Officer Common Stock 2020-01-02 4 M false 11294.00 9.49 A 19598.00 D Common Stock 2020-01-02 4 S false 11294.00 15.036 D 8304.00 D Stock Option (Right to Buy) 9.49 2020-01-02 4 M false 11294.00 0.00 D 2028-04-25 Common Stock 11294.00 224831.00 D This trade is pursuant to an active 10b5-1 plan. This transaction was executed in multiple trades at prices ranging from $15.00 to $15.09. The price reported above reflects the weighted average price. The reporting person hereby undertakes to provide upon request by the staff of the U.S. Securities and Exchange Commission, the issuer or a security holder of the issuer, full information regarding the number of shares and prices at which the transaction was effected. 25% vested on February 16, 2019 with the remaining 75% vesting in 12 equal quarterly installments thereafter. /s/ Zoran Zdraveski, Attorney-in-Fact for John C. Davis, Jr. 2020-01-03