Generation BioGBIO
13F holders, Q4 2025 (December 31)At the end of Q4 2025, 46 institutions reported holding Generation Bio Co. (GBIO) in their 13F filings, up 10 from Q3 2025. 11 opened new positions and 3 sold out. The largest holders were Atlas Venture Life Science Advisors, LLC ($4.7M), SymBiosis Capital Partners, LLC ($3.8M) and Opaleye Management Inc. ($1.8M). 3 famous investors held it, including Jim Simons / Peter Brown (0.0% of Renaissance Technologies's portfolio), Israel Englander (0.0% of Millennium Management's portfolio) and Ken Griffin (0.0% of Citadel Advisors's portfolio).
- Company
- Generation Bio Co.
- CUSIP
- 37148K209
- Latest filing quarter
- Q4 2025
History
Number of 13F holders
Total Exit/New Position Q3 2025 → Q4 2025
| Institutions | Total Value | |
|---|---|---|
| New Positions | 11 | $8.0M |
| Exits | 3 | $1.8M |
All 13F filers, Q3 2025 → Q4 2025: 1,478,410 shares bought and 947,384 shares sold, net +531,026 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 46 holders
| Atlas Venture Life Science Advisors, LLC | 0.54% | New | 827,946 | $4.7M |
| SymBiosis Capital Partners, LLC | 3.45% | — | 665,000 | $3.8M |
| Opaleye Management Inc. | 0.23% | New | 310,000 | $1.8M |
| Renaissance Technologies | 0.00% | Reduce -16.5% | 287,614 | $1.6M |
| Vanguard Group Inc. | 0.00% | No change | 229,833 | $1.3M |
| T. Rowe Price Associates Inc. | 0.00% | Reduce -63.6% | 209,641 | $1.2M |
| Siren, L.L.C. | 0.03% | Reduce -32.2% | 201,419 | $1.1M |
| UBS Group AG | 0.00% | Add +10.8% | 164,716 | $936K |
| Morgan Stanley | 0.00% | Reduce -1.8% | 161,378 | $917K |
| Marshall Wace, LLP | 0.00% | Reduce -35.8% | 140,294 | $797K |
| Acadian Asset Management LLC | 0.00% | Reduce -5.1% | 121,029 | $686K |
| Yiheng Capital Management, L.P. | 0.26% | No change | 105,524 | $599K |
| Rangeley Capital, LLC | 0.49% | New | 98,280 | $558K |
| Goldman Sachs Group Inc. | 0.00% | Reduce -22.8% | 91,527 | $520K |
| Millennium Management | 0.00% | Reduce -9.0% | 88,563 | $503K |
| Bank of America Corp. | 0.00% | Add +0.0% | 84,842 | $482K |
| BlackRock, Inc. | 0.00% | Reduce -0.1% | 60,070 | $341K |
| Geode Capital Management, LLC | 0.00% | Add +4.0% | 51,795 | $294K |
| Two Sigma Investments, LP | 0.00% | Add +306.3% | 50,557 | $287K |
| Citadel Advisors | 0.00% | Add +0.1% | 47,245 | $268K |
| DRW Securities, LLC | 0.02% | New | 43,812 | $249K |
| Deltec Asset Management LLC | 0.03% | New | 32,650 | $185K |
| TD Asset Management Inc | 0.00% | No change | 26,708 | $152K |
| Torno Capital, LLC | 0.06% | New | 25,000 | $142K |
| Lynx1 Capital Management LP | 0.03% | New | 25,000 | $142K |
| ADAR1 Capital Management, LLC | 0.01% | No change | 22,144 | $126K |
| State Street Corp. | 0.00% | No change | 19,993 | $114K |
| Shay Capital LLC | 0.02% | Add +90.5% | 19,839 | $113K |
| CSS LLC | 0.02% | New | 17,464 | $99K |
| Northern Trust Corp. | 0.00% | Add +28.2% | 17,058 | $97K |
| Palo Alto Investors LP | 0.01% | New | 15,047 | $85K |
| Manufacturers Life Insurance Company, The | 0.00% | No change | 14,398 | $80K |
| XTX Topco Ltd | 0.00% | Add +15.7% | 13,122 | $75K |
| Two Sigma Advisers, LP | 0.00% | New | 11,930 | $68K |
| Seven Fleet Capital Management LP | 0.02% | — | 5,376 | $31K |
| FMR LLC | 0.00% | Reduce -79.9% | 2,617 | $15K |
| Royal Bank of Canada | 0.00% | Reduce -8.9% | 992 | $6K |
| JPMorgan Chase & Co. | 0.00% | Add +0.3% | 689 | $4K |
| Rockefeller Capital Management L.P. | 0.00% | Add +42.9% | 500 | $3K |
| Sterling Capital Management LLC | 0.00% | No change | 194 | $1K |
| BNP Paribas Financial Markets | 0.00% | Reduce -4.5% | 147 | $835 |
| SBI Securities Co., Ltd. | 0.00% | No change | 53 | $301 |
| Wells Fargo & Company | 0.00% | No change | 50 | $284 |
| Optiver Holding B.V. | 0.00% | Reduce -60.0% | 2 | $11 |
| Smartleaf Asset Management LLC | 0.00% | New | 1 | $6 |
| Cwm, LLC | 0.00% | Reduce -75.0% | 1 | $0 |
"% of holder's portfolio" is GBIO's weight in each manager's 13F, not the share of Generation Bio Co. the manager owns.