X0508 4/A 2025-01-03 2025-01-07 false 0001860782 2seventy bio, Inc. TSVT 0002009134 Snow Jessica 60 BINNEY STREET CAMBRIDGE MA 02142 false true false false See Remarks true Common Stock 2025-01-06 4 S false 1838.00 2.7944 D 150527.00 D On January 7, 2025, the Reporting Person filed a Form 4 which inadvertently reported the incorrect number of shares sold on January 6, 2025 pursuant to a Rule 10b5-1 trading plan (the "Original Form 4"). The Original Form 4 reported a sale of 5,000 shares and this Form 4 amendment is being filed to report the correct number of shares sold as 1,838. Title: Senior Vice President of Quality and Enabling Functions /s/ Iya Kessler, Attorney-in-Fact 2025-01-22