Security key
37148K100
GENERATION BIO CO. - COMMON STOCK, $0.0001 PAR VALUE (GBIO)
CUSIP: 37148K100
Q3 2023 13F Holders as of 30 Sep 2023
- Security type / class
- Equity / COMMON STOCK, $0.0001 PAR VALUE
- Total 13F shares
- 57,206,477
- Total 13F value
- $216,814,886
- Share change
- -90,312
- Put/Call ratio
- 256%
- SEC-reported price per share
- $3.79
- Number of holders
- 75
- Value change
- -$1,287,599
- Number of buys
- 27
- Number of sells
- 33
- Shares outstanding
- 67,017,829
Holder snapshot
7 signals
Open additional details 1 more signal available
Security identity
Names, identifiers, and filing context for this profile.
1 source field
Report period
Q3 2023
Institutions
75
Top holders
10
GBIO full security history
Ownership snapshot
Full 13F holder table
Newer quarter: Q4 2025
Generation Bio Co. SEC filings
Generation Bio Co. company facts
Broader feeds
Reporting periods
Holder history for CUSIP 37148K100
Recent filing periods:
Ownership snapshot
Top reported holders of GBIO - GENERATION BIO CO. - COMMON STOCK, $0.0001 PAR VALUE (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
ATLAS VENTURE ASSOCIATES ...
Disclosed value leader
FMR LLC
Comparable rows
0/15
Latest evidence
30 Jun 2023
3/4/5
13F
Highest disclosed value: $47,424,119
15 rows are not safely comparable across share classes.
Showing 1-6 of 15 holder rows.
Quick read
FMR LLC has the largest disclosed position value at $47.42M.
0 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens FMR LLC's linked filing trail.
Disclosed position value
Top 5
ATLAS VENTURE ASSOCIATES X, L.P.
$1.2K
FMR LLC
$47.42M
Atlas Venture Life Science Adviso...
$45.54M
PRICE T ROWE ASSOCIATES INC /MD/
$41.22M
Bellevue Group AG
$19.91M
Value bars compare disclosed positions; verify each figure against the linked filing evidence.
Detailed SEC evidence table Showing 1-6 of 15 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| ATLAS VENTURE ASSOCIATES X, L.P. |
3/4/5
10%+ Owner
|
—
denominator unverified
|
$1,161
608 shares
|
— | 27 Sep 2021 |
| FMR LLC |
13F
Company
|
—
denominator unverified
|
$47,424,119
8,622,567 shares
|
— | 30 Jun 2023 |
| Atlas Venture Life Science Advisors, LLC |
13F
Company
|
—
denominator unverified
|
$45,537,162
8,279,484 shares
|
— | 30 Jun 2023 |
| PRICE T ROWE ASSOCIATES INC /MD/ |
13F
Company
|
—
denominator unverified
|
$41,219,000
7,494,184 shares
|
— | 30 Jun 2023 |
| Bellevue Group AG |
13F
Company
|
—
denominator unverified
|
$19,911,540
3,620,280 shares
|
— | 30 Jun 2023 |
| BlackRock Finance, Inc. |
13F
Company
|
—
denominator unverified
|
$19,453,294
3,536,962 shares
|
— | 30 Jun 2023 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
13F holder rows
Institutional holders as of Q3 2023
Investor-level positions for this CUSIP, loaded as an interactive table.
Institutions
75
Shares
57,206,477
Rows available
75
| Investor | Option | Weight % | Change % | SEC-reported value | * Price | Shares | Share Change | Activity | Report Period |
|---|
* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.
Compare Q3 2023 vs Q1 2026 Across Filers
Q1 2026 holders
1
Q3 2023 holders
75
Holder diff
74
| Investor | Q1 2026 Shares | Q3 2023 Shares | Share Diff | Share Chg % | Q1 2026 value | Q3 2023 value | Value change | Value Chg % |
|---|
Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).
Quarterly Holders Trend
Quarterly Value Trend
Quarterly Shares Trend