X0306 4 2022-01-10 false 0001293971 bluebird bio, Inc. BLUE 0001350360 Cole Jason C/O BLUEBIRD BIO, INC. 60 BINNEY STREET CAMBRIDGE MA 02142 false true false true Chief Operating and Legal Officer Common Stock 2022-01-10 4 S false 1584.00 9.4022 D 189575.00 D Common Stock 2022-01-11 4 S false 3387.00 9.6426 D 186188.00 D Shares were sold to cover tax withholding obligations incurred in connection with the vesting of Restricted Stock Units. The range in prices for the transaction reported on this line was $9.385 to $9.42. The average weighted price was $9.4022. The reporting person will provide, upon request by the SEC, the issuer or security holder of the issuer, full information regarding the number of shares sold at each separate price. The range in prices for the transaction reported on this line was $9.48 to $9.83. The average weighted price was $9.6426. The reporting person will provide, upon request by the SEC, the issuer or security holder of the issuer, full information regarding the number of shares sold at each separate price. /s/ Helen C. Fu, Attorney-in-Fact 2022-01-12