Generation BioGBIO
13F holders, Q3 2025 (September 30)At the end of Q3 2025, 36 institutions reported holding Generation Bio Co. (GBIO) in their 13F filings, up 32 from Q2 2025. 7 opened new positions and 2 sold out. The largest holders were T. Rowe Price Associates Inc. ($3.5M), Renaissance Technologies ($2.1M) and Siren, L.L.C. ($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 Q2 2025 → Q3 2025
| Institutions | Total Value | |
|---|---|---|
| New Positions | 7 | $877K |
| Exits | 2 | $167 |
All 13F filers, Q2 2025 → Q3 2025: 512,125 shares bought and 567,696 shares sold, net −55,571 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 36 holders
| T. Rowe Price Associates Inc. | 0.00% | Reduce -31.8% | 576,789 | $3.5M |
| Renaissance Technologies | 0.00% | Add +33.4% | 344,263 | $2.1M |
| Siren, L.L.C. | 0.07% | No change | 296,892 | $1.8M |
| Vanguard Group Inc. | 0.00% | No change | 229,833 | $1.4M |
| Marshall Wace, LLP | 0.00% | Add +88.0% | 218,461 | $1.3M |
| Baker Bros. Advisors LP | 0.01% | No change | 194,493 | $1.2M |
| Morgan Stanley | 0.00% | Add +80.0% | 164,270 | $1.0M |
| UBS Group AG | 0.00% | Add +68.1% | 148,721 | $910K |
| Acadian Asset Management LLC | 0.00% | Add +3.4% | 127,506 | $779K |
| Goldman Sachs Group Inc. | 0.00% | Add +11.4% | 118,583 | $726K |
| Yiheng Capital Management, L.P. | 0.21% | No change | 105,524 | $646K |
| Cantor Fitzgerald, L. P. | 0.01% | New | 99,000 | $606K |
| Millennium Management | 0.00% | Reduce -8.3% | 97,354 | $596K |
| Bank of America Corp. | 0.00% | Reduce -2.7% | 84,817 | $519K |
| BlackRock, Inc. | 0.00% | Reduce -48.3% | 60,116 | $368K |
| Geode Capital Management, LLC | 0.00% | No change | 49,805 | $305K |
| Citadel Advisors | 0.00% | Add +145.6% | 47,197 | $289K |
| TD Asset Management Inc | 0.00% | Reduce -21.6% | 26,708 | $163K |
| ADAR1 Capital Management, LLC | 0.01% | New | 22,144 | $136K |
| State Street Corp. | 0.00% | Reduce -3.0% | 19,993 | $122K |
| Manufacturers Life Insurance Company, The | 0.00% | No change | 14,398 | $88K |
| Northern Trust Corp. | 0.00% | No change | 13,306 | $81K |
| FMR LLC | 0.00% | Reduce -94.4% | 13,031 | $80K |
| Two Sigma Investments, LP | 0.00% | Add +17.4% | 12,442 | $76K |
| XTX Topco Ltd | 0.00% | New | 11,344 | $69K |
| Shay Capital LLC | 0.01% | New | 10,414 | $64K |
| Royal Bank of Canada | 0.00% | Add +261.2% | 1,089 | $7K |
| JPMorgan Chase & Co. | 0.00% | Add +58.6% | 687 | $4K |
| Citigroup Inc. | 0.00% | Reduce -35.5% | 668 | $4K |
| Rockefeller Capital Management L.P. | 0.00% | New | 350 | $2K |
| Sterling Capital Management LLC | 0.00% | Reduce -0.5% | 194 | $1K |
| BNP Paribas Financial Markets | 0.00% | Reduce -9.7% | 154 | $942 |
| SBI Securities Co., Ltd. | 0.00% | Reduce -90.0% | 53 | $324 |
| Wells Fargo & Company | 0.00% | Reduce -67.4% | 50 | $306 |
| Optiver Holding B.V. | 0.00% | New | 5 | $31 |
| Cwm, LLC | 0.00% | New | 4 | $0 |
"% of holder's portfolio" is GBIO's weight in each manager's 13F, not the share of Generation Bio Co. the manager owns.