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Ownership Document
|
| Schema Version: X0508 |
| Document Type: 4 |
| Period of Report: 3/26/24 |
| Not Subject to Section 16: 0 |
| Issuer: |
| Issuer CIK: 1860782 |
| Issuer Name: 2seventy bio, Inc. |
| Issuer Trading Symbol: TSVT |
| Reporting Owner: |
| Reporting Owner ID: |
| | Owner CIK: 1534261 |
| | Owner Name: Casdin Capital, LLC |
| Reporting Owner Address: |
| | Owner Street 1: 1350 AVENUE OF THE AMERICAS |
| | Owner Street 2: SUITE 2600 |
| | Owner City: NEW YORK |
| | Owner State: NY |
| | Owner ZIP Code: 10019 |
| | Owner State Description: |
| Reporting Owner Relationship: |
| | Is Director? Yes |
| | Is Officer? No |
| | Is Ten Percent Owner? No |
| | Is Other? No |
| | Officer Title: |
| | Other Text: |
| Reporting Owner: |
| Reporting Owner ID: |
| | Owner CIK: 1534265 |
| | Owner Name: Casdin Partners Master Fund, L.P. |
| Reporting Owner Address: |
| | Owner Street 1: 1350 AVENUE OF THE AMERICAS |
| | Owner Street 2: SUITE 2600 |
| | Owner City: NEW YORK |
| | Owner State: NY |
| | Owner ZIP Code: 10019 |
| | Owner State Description: |
| Reporting Owner Relationship: |
| | Is Director? Yes |
| | Is Officer? No |
| | Is Ten Percent Owner? No |
| | Is Other? No |
| | Officer Title: |
| | Other Text: |
| Reporting Owner: |
| Reporting Owner ID: |
| | Owner CIK: 1534260 |
| | Owner Name: Casdin Partners GP, LLC |
| Reporting Owner Address: |
| | Owner Street 1: 1350 AVENUE OF THE AMERICAS |
| | Owner Street 2: SUITE 2600 |
| | Owner City: NEW YORK |
| | Owner State: NY |
| | Owner ZIP Code: 10019 |
| | Owner State Description: |
| Reporting Owner Relationship: |
| | Is Director? Yes |
| | Is Officer? No |
| | Is Ten Percent Owner? No |
| | Is Other? No |
| | Officer Title: |
| | Other Text: |
| Reporting Owner: |
| Reporting Owner ID: |
| | Owner CIK: 1534264 |
| | Owner Name: Casdin Eli |
| Reporting Owner Address: |
| | Owner Street 1: 1350 AVENUE OF THE AMERICAS |
| | Owner Street 2: SUITE 2600 |
| | Owner City: NEW YORK |
| | Owner State: NY |
| | Owner ZIP Code: 10019 |
| | Owner State Description: |
| Reporting Owner Relationship: |
| | Is Director? Yes |
| | Is Officer? No |
| | Is Ten Percent Owner? No |
| | Is Other? No |
| | Officer Title: |
| | Other Text: |
| Aff 10b5 One: 0 |
| Non-Derivative Table: |
| Non-Derivative Transaction: |
| | Security Title: |
| | | Value: Common Stock, par value $0.0001 per share |
| | Transaction Date: |
| | | Value: 3/26/24 |
| | Deemed Execution Date: |
| | Transaction Coding: |
| | | Transaction Form Type: 4 |
| | | Transaction Code: P |
| | | Equity Swap Involved? No |
| | Transaction Timeliness: |
| | Transaction Amounts: |
| | | Transaction Shares: |
| Value: 40,000 |
| | | Transaction Price Per Share: |
| Value: 5.0998 |
| Footnote ID: F1 |
| | | Transaction Acquired-Disposed Code: |
| Value: A |
| | Post-Transaction Amounts: |
| | | Shares Owned Following Transaction: |
| Value: 2,000,000 |
| | Ownership Nature: |
| | | Direct or Indirect Ownership: |
| Value: I |
| | | Nature of Ownership: |
| Value: See footnote. |
| Footnote ID: F2 |
| Non-Derivative Holding: |
| | Security Title: |
| | | Value: Common Stock, par value $0.0001 per share |
| | | Footnote ID: F3 |
| | Post-Transaction Amounts: |
| | | Shares Owned Following Transaction: |
| Value: 16,600 |
| | Ownership Nature: |
| | | Direct or Indirect Ownership: |
| Value: D |
| Footnote ID: F4 |
| Footnotes: |
| Footnote - F1: The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $4.9 to $5.41. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote. |
| Footnote - F2: The securities are owned directly by Casdin Partners Master Fund, L.P. (the "Master Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to the Master Fund ("Casdin"), (ii) Casdin Partners GP, LLC, the general partner of the Master Fund (the "GP"), and (iii) Eli Casdin, the managing member of Casdin and the GP. |
| Footnote - F3: This restricted stock unit award vests ratable over three years in annual installments with the first installment vesting on March 20, 2025, subject to the Reporting Person's continued service through the applicable vesting date. |
| Footnote - F4: The securities are owned directly by Eli Casdin. |
| Remarks: Eli Casdin has been deputized to represent the Reporting Persons on the board of directors of the Issuer. By virtue of Mr. Casdin's representation, for purposes of Section 16 of the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons may be deemed directors by deputization of the Issuer. Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. |
| Owner Signature: |
| Signature Name: Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member |
| Signature Date: 3/28/24 |
| Owner Signature: |
| Signature Name: Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member |
| Signature Date: 3/28/24 |
| Owner Signature: |
| Signature Name: Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member |
| Signature Date: 3/28/24 |
| Owner Signature: |
| Signature Name: /s/ Eli Casdin, Eli Casdin |
| Signature Date: 3/28/24 |
