Investor Atlas Venture Fund X, L.P.
13D/G Filings

This page shows a list of all the recent 13D/G filings made by Atlas Venture Fund X, L.P. . Schedule 13D is commonly referred to as a “beneficial ownership report.” The term "beneficial owner" is defined under SEC rules. It includes any person who directly or indirectly shares voting power or investment power (the power to sell the security).

When a person or group of persons acquires beneficial ownership of more than 5% of a voting class of a company’s equity securities, they are required to file a Schedule 13D within ten days after the purchase. Click the link icon to see the full transaction history.

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Date Form Target Prev
Shares		 Current
Shares		 Change
(Percent)		 Ownership
(Percent)		 Change
(Percent)
2025-08-15 13D/A IRON / Disc Medicine, Inc. 1,402,186 1,084,527
2025-07-29 13D/A IMA / ImageneBio, Inc. 241,800
2024-11-14 13G/A KYMR / Kymera Therapeutics, Inc. 4,968,114 4,173,216
2024-10-28 13D/A TECX / Tectonic Therapeutic, Inc. 67,567
2024-04-01 13D QTTB / Q32 Bio Inc. 864,261
2024-02-09 13G/A GBIO / Generation Bio Co. 7,111,939 7,111,939
2024-02-09 13G/A KYMR / Kymera Therapeutics, Inc. 5,066,925 4,968,114
2024-01-25 13D/A IRON / Disc Medicine, Inc. 1,593,785 1,402,186
2023-09-21 13D/A IRON / Disc Medicine, Inc. 2,237,303 1,593,785
2023-09-15 13D/A DNTH / Dianthus Therapeutics, Inc. 186,089
2023-02-14 13D/A IRON / Disc Medicine, Inc. 2,237,303
2023-02-14 13G/A KYMR / Kymera Therapeutics, Inc. 5,763,012 5,066,925
2022-12-06 13D/A REPL / Replimune Group, Inc. 2,164,037 1,498,635
2022-09-14 13D/A REPL / Replimune Group, Inc. 2,524,866 2,164,037
2022-05-05 13D/A MGTA / Magenta Therapeutics Inc 3,357,340 2,977,448
2022-02-11 13G/A KYMR / Kymera Therapeutics, Inc. 7,948,982 5,763,012
2022-02-11 13D IKNA / Ikena Oncology, Inc. 2,901,609
2022-02-11 13G/A GBIO / Generation Bio Co. 10,111,939 7,111,939
2021-02-17 13D/A MGTA / Magenta Therapeutics Inc 4,117,125 3,357,340
2021-02-16 13D/A SPRO / Spero Therapeutics, Inc. 1,031,160
2021-02-16 13G GBIO / Generation Bio Co. 10,111,939
2021-02-16 13D GMTX / Gemini Therapeutics Inc 4,015,045
2021-02-16 13G KYMR / Kymera Therapeutics, Inc. 7,948,982
2020-09-17 13D/A REPL / Replimune Group, Inc. 2,961,473 2,524,866
2020-07-14 13D MGTA / Magenta Therapeutics Inc 4,117,125 4,117,125
2020-07-07 13D/A REPL / Replimune Group, Inc. 3,398,080 2,961,473
2020-06-19 13D/A REPL / Replimune Group, Inc. 3,834,587 3,398,080
2020-02-13 13G/A MGTA / Magenta Therapeutics Inc 4,843,625 4,117,125
2019-11-25 13D REPL / Replimune Group, Inc. 4,453,386 3,834,587
2019-07-30 13D AVRO / AVROBIO, Inc. 47,564,781 4,756,478
2019-02-13 13G AVRO / AVROBIO, Inc. 4,756,478
2019-02-13 13G MGTA / Magenta Therapeutics Inc 4,843,625
2019-02-13 13G REPL / Replimune Group, Inc. 4,453,386
2018-03-14 13D SPRO / Spero Therapeutics, Inc. 1,031,160