Latest Period
Q4 2025
Security Snapshot
Generation Bio Co. - COMMON STOCK (GBIO) Institutional Ownership
CUSIP: 37148K209
13F Institutional Holders and Ownership History from Q2 2025 to Q1 2026
Institutions Reporting
45
Shares (Excl. Options)
4,312,052
Price
$5.68
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- Type / Class
- Equity / COMMON STOCK
- Symbol
- GBIO
- Shares outstanding
- 6,762,613
- Price per share
- $5.34
- All holders as of 31 Dec 2025
- Q4 2025
- Total 13F shares
- 4,312,052
- Total reported value
- $24,490,431
- % of total 13F portfolios
- 0%
- Share change
- +531,035
- Value change
- +$2,886,466
- Number of holders
- 45
- Price from insider filings
- $5.34
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors
Quick Takeaways
- GBIO - Generation Bio Co. - COMMON STOCK is tracked under CUSIP 37148K209.
- 45 institutions reported positions in Q4 2025.
- 3 significant owners is listed from Schedule 13D/13G reporting.
What Changed
- Holder count moved from 45 to 0 between Q4 2025 and Q1 2026.
- Reported value moved from $24,490,431 to $0.
Why This Matters
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Source Evidence
Source: SEC Form 13F
Open SEC Evidence
Latest holder context comes from 45 institutions filings for Q4 2025.
Investment Quick Answers
What is CUSIP 37148K209?
CUSIP 37148K209 identifies GBIO - Generation Bio Co. - COMMON STOCK in SEC 13F datasets.
Where can I see the latest institutional holders?
Review the Q4 2025 holders report and the ownership history table below.
Next ownership checks
Use the next link that matches the question you still need to answer about this security.
- Latest 13F filings when you want to inspect fresh institutional portfolio moves.
- Latest Schedule 13D/13G reports when you need large-owner changes outside the 13F cycle.
- All institutional ownership pages to compare this security with other holder-history pages.
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 37148K209:
Significant Owners of Generation Bio Co. - COMMON STOCK (GBIO) based on Schedule 13D/G filings
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| SymBiosis Capital Partners, LLC | 6.3% | $2,582,018 | 421,926 | SymBiosis Capital Partners, LLC | 30 Sep 2025 | |||
| RENAISSANCE TECHNOLOGIES LLC | 4.3% | -17% | $1,576,125 | -$310,437 | 287,614 | -16% | Renaissance Technologies LLC | 31 Dec 2025 |
| PRICE T ROWE ASSOCIATES INC /MD/ | 3.1% | -61% | $1,148,833 | -$2,011,971 | 209,641 | -64% | T. Rowe Price Associates, Inc. | 31 Dec 2025 |
As of 31 Dec 2025, 45 institutional investors reported holding 4,312,052 shares of Generation Bio Co. - COMMON STOCK (GBIO). This represents 64% of the company’s total 6,762,613 outstanding shares.
Top 25 Institutional Shareholders
The largest institutional shareholders of Generation Bio Co. - COMMON STOCK (GBIO) together control 61% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| Atlas Venture Life Science Advisors, LLC | 12% | 827,946 | 0.54% | $4,702,732 | |
| SymBiosis Capital Partners, LLC | 9.8% | 665,000 | 0% | 3.9% | $3,777,200 |
| Opaleye Management Inc. | 4.6% | 310,000 | 0.23% | $1,760,800 | |
| RENAISSANCE TECHNOLOGIES LLC | 4.3% | 287,614 | -16% | 0% | $1,633,648 |
| VANGUARD GROUP INC | 3.4% | 229,833 | 0% | 0% | $1,305,451 |
| PRICE T ROWE ASSOCIATES INC /MD/ | 3.1% | 209,641 | -64% | 0% | $1,191,000 |
| Siren, L.L.C. | 3% | 201,419 | -32% | 0.03% | $1,144,060 |
| UBS Group AG | 2.4% | 164,716 | +11% | 0% | $935,587 |
| MORGAN STANLEY | 2.4% | 161,378 | -1.8% | 0% | $916,627 |
| MARSHALL WACE, LLP | 2.1% | 140,294 | -36% | 0% | $796,870 |
| ACADIAN ASSET MANAGEMENT LLC | 1.8% | 121,029 | -5.1% | 0% | $686,000 |
| Yiheng Capital Management, L.P. | 1.6% | 105,524 | 0% | 0.26% | $599,376 |
| Rangeley Capital, LLC | 1.5% | 98,280 | 0.49% | $558,230 | |
| GOLDMAN SACHS GROUP INC | 1.4% | 91,527 | -23% | 0% | $519,873 |
| MILLENNIUM MANAGEMENT LLC | 1.3% | 88,563 | -9% | 0% | $503,038 |
| BANK OF AMERICA CORP /DE/ | 1.3% | 84,842 | +0.03% | 0% | $481,903 |
| BlackRock, Inc. | 0.89% | 60,070 | -0.08% | 0% | $341,197 |
| GEODE CAPITAL MANAGEMENT, LLC | 0.77% | 51,795 | +4% | 0% | $294,268 |
| TWO SIGMA INVESTMENTS, LP | 0.75% | 50,557 | +306% | 0% | $287,164 |
| CITADEL ADVISORS LLC | 0.7% | 47,245 | +0.1% | 0% | $268,352 |
| DRW Securities, LLC | 0.65% | 43,812 | 0.02% | $248,852 | |
| DELTEC ASSET MANAGEMENT LLC | 0.48% | 32,650 | 0.03% | $185,452 | |
| TD Asset Management Inc | 0.39% | 26,708 | 0% | 0% | $151,701 |
| Lynx1 Capital Management LP | 0.37% | 25,000 | 0.03% | $142,000 | |
| TORNO CAPITAL, LLC | 0.37% | 25,000 | 0.13% | $142,000 |