Quick Takeaways
- Generation Bio Co. has 20 insiders with reported activity on this page.
- No net insider buy/sell flow is currently reported for the last year.
- Recent transaction rows are available for direct filing-level review.
Insider Transactions Reported by 20 Insiders of Generation Bio Co.
- Location
- Cambridge, MA
What Changed
- No meaningful buy/sell imbalance is currently visible in the one-year window.
- Activity will update as new Forms 3/4/5 are filed.
Why This Matters
- This page gives a plain-language issuer insider context before you inspect transaction-level evidence.
- Use the filing links below to verify timestamps, codes, and ownership impacts directly from SEC forms.
Source Evidence
Filed on Form 4
See Original Filing
Issuer insider activity is sourced from SEC Forms 3, 4, and 5.
Insider trading overview
Last 12 monthsInsider buy and sell flow is broadly balanced over the last 12 months. No Buy or Sell transactions have been reported since 11 May 2025.
Buys
$0
Shares: 0
Insiders: 0
Sells
$0
Shares: 0
Insiders: 0
Net
$0
Shares: 0
Insiders: 0
| Window (months) | Buy shares | Sell shares | Buy $ | Sell $ | Net $ |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Generation Bio Co. executives and other stock owners filed with the SEC include:
Top shareholders of Generation Bio Co. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Ownership % is shown only when it is directly reported or safely comparable across share classes.
Methodology: rows are grouped by holder and ranked by the holder's primary source value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
| Holder | Source | Role / Reporting | Ownership % | Shares | Holdings Value | 12M Net Δ | As of | Details |
|---|---|---|---|---|---|---|---|---|
| Atlas Venture Life Science Advisors, LLC |
13F
|
Company |
12%
|
827,946
|
$4,702,732 | — | 31 Dec 2025 | |
| SymBiosis Capital Partners, LLC |
13F
13D/G
|
Company |
6.3%
from 13D/G
|
665,000
|
$3,777,200 | — | 31 Dec 2025 | |
| Opaleye Management Inc. |
13F
|
Company |
4.6%
|
310,000
|
$1,760,800 | — | 31 Dec 2025 | |
| RENAISSANCE TECHNOLOGIES LLC |
13F
13D/G
|
Company |
4.3%
from 13D/G
|
287,614
|
$1,633,648 | — | 31 Dec 2025 | |
| Matthew Stanton |
3/4/5
|
CHIEF SCIENTIFIC OFFICER |
—
mixed-class rows
|
423,028
mixed-class rows
|
$1,372,339 | — | 10 Jan 2025 | |
| VANGUARD GROUP INC |
13F
|
Company |
3.4%
|
229,833
|
$1,305,451 | — | 31 Dec 2025 | |
| PRICE T ROWE ASSOCIATES INC /MD/ |
13F
13D/G
|
Company · T. Rowe Price Associates, Inc. |
3.1%
from 13D/G
|
209,641
|
$1,191,000 | — | 31 Dec 2025 | |
| Siren, L.L.C. |
13F
|
Individual |
3%
|
201,419
|
$1,144,060 | — | 31 Dec 2025 | |
| UBS Group AG |
13F
|
Company |
2.4%
|
164,716
|
$935,587 | — | 31 Dec 2025 | |
| MORGAN STANLEY |
13F
|
Company |
2.4%
|
161,378
|
$916,627 | — | 31 Dec 2025 | |
| Matthew Norkunas |
3/4/5
|
CHIEF FINANCIAL OFFICER |
—
mixed-class rows
|
219,671
mixed-class rows
|
$880,215 | — | 10 Jan 2025 | |
| Phillip Samayoa |
3/4/5
|
CHIEF SCIENTIFIC OFFICER |
—
mixed-class rows
|
265,741
mixed-class rows
|
$835,200 | — | 31 Oct 2025 | |
| MARSHALL WACE, LLP |
13F
|
Company |
2.1%
|
140,294
|
$796,870 | — | 31 Dec 2025 | |
| Antoinette Paone |
3/4/5
|
CHIEF OPERATING OFFICER |
—
mixed-class rows
|
255,483
mixed-class rows
|
$766,026 | — | 31 Oct 2025 | |
| FMR LLC |
13D/G
13F
|
Company |
3.5%
|
2,345,624
|
$750,600 | -$729,735 | 30 Jun 2025 | |
| Douglas Kerr |
3/4/5
|
CHIEF MEDICAL OFFICER |
—
class O/S missing
|
385,628
|
$732,693 | — | 29 Jan 2024 | |
| ACADIAN ASSET MANAGEMENT LLC |
13F
|
Company |
1.8%
|
121,029
|
$686,000 | — | 31 Dec 2025 | |
| Yiheng Capital Management, L.P. |
13F
|
Company |
1.6%
|
105,524
|
$599,376 | — | 31 Dec 2025 | |
| Rangeley Capital, LLC |
13F
|
Company |
1.5%
|
98,280
|
$558,230 | — | 31 Dec 2025 | |
| GOLDMAN SACHS GROUP INC |
13F
|
Company |
1.4%
|
91,527
|
$519,873 | — | 31 Dec 2025 | |
| MILLENNIUM MANAGEMENT LLC |
13F
|
Company |
1.3%
|
88,563
|
$503,038 | — | 31 Dec 2025 | |
| BANK OF AMERICA CORP /DE/ |
13F
|
Company |
1.3%
|
84,842
|
$481,903 | — | 31 Dec 2025 | |
| BlackRock, Inc. |
13D/G
13F
|
Company |
1.7%
|
1,152,047
|
$414,737 | $0 | 30 Jun 2025 | |
| GEODE CAPITAL MANAGEMENT, LLC |
13F
|
Company |
0.77%
|
51,795
|
$294,268 | — | 31 Dec 2025 | |
| TWO SIGMA INVESTMENTS, LP |
13F
|
Company |
0.75%
|
50,557
|
$287,164 | — | 31 Dec 2025 | |
| Anthony G. Quinn |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Catherine Stehman-Breen |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Charles A. Rowland Jr. |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Dannielle Appelhans |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Donald William Nicholson |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Gustav Christensen |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Jason P. Rhodes |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Jeffrey M. Jonas |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| Ronald Harold Wilfred Cooper |
3/4/5
|
Director | — | — | $275,400 | — | 09 Feb 2026 | |
| CITADEL ADVISORS LLC |
13F
|
Company |
0.7%
|
47,245
|
$268,352 | — | 31 Dec 2025 | |
| DRW Securities, LLC |
13F
|
Company |
0.65%
|
43,812
|
$248,852 | — | 31 Dec 2025 | |
| DELTEC ASSET MANAGEMENT LLC |
13F
|
Company |
0.48%
|
32,650
|
$185,452 | — | 31 Dec 2025 | |
| TD ASSET MANAGEMENT INC |
13F
|
Company |
0.39%
|
26,708
|
$151,701 | — | 31 Dec 2025 | |
| Lynx1 Capital Management LP |
13F
|
Company |
0.37%
|
25,000
|
$142,000 | — | 31 Dec 2025 | |
| TORNO CAPITAL, LLC |
13F
|
Company |
0.37%
|
25,000
|
$142,000 | — | 31 Dec 2025 | |
| ADAR1 Capital Management, LLC |
13F
|
Company |
0.33%
|
22,144
|
$125,778 | — | 31 Dec 2025 | |
| STATE STREET CORP |
13F
|
Company |
0.3%
|
19,993
|
$113,560 | — | 31 Dec 2025 | |
| Shay Capital LLC |
13F
|
Company |
0.29%
|
19,839
|
$112,686 | — | 31 Dec 2025 | |
| CSS LLC/IL |
13F
|
Company |
0.26%
|
17,464
|
$99,196 | — | 31 Dec 2025 | |
| NORTHERN TRUST CORP |
13F
|
Company |
0.25%
|
17,058
|
$96,889 | — | 31 Dec 2025 | |
| Tracy Zimmermann |
3/4/5
|
CHIEF DEVELOPMENT OFFICER |
—
class O/S missing
|
49,164
|
$93,412 | — | 29 Jan 2024 | |
| Palo Alto Investors LP |
13F
|
Company |
0.22%
|
15,047
|
$85,467 | — | 31 Dec 2025 | |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE |
13F
|
Company |
0.21%
|
14,398
|
$80,485 | — | 31 Dec 2025 | |
| XTX Topco Ltd |
13F
|
Company |
0.19%
|
13,122
|
$74,533 | — | 31 Dec 2025 | |
| TWO SIGMA ADVISERS, LP |
13F
|
Company |
0.18%
|
11,930
|
$67,762 | — | 31 Dec 2025 |
Recent Insider Transactions by Companies or Individuals for Generation Bio Co.
Showing up to 300 most recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | Value $ | * Price $ | Shares | Shares Owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Atlas Venture Fund X, L.P. | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -116,753 | 0 | 09 Feb 2026 | See footnote | ||
| Atlas Venture Fund X, L.P. | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -711,193 | 0 | 09 Feb 2026 | Direct | ||
| Catherine Stehman-Breen | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -4,752 | 0 | 09 Feb 2026 | Direct | ||
| Catherine Stehman-Breen | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -20,120 | 0 | 09 Feb 2026 | Direct | ||
| Charles A. Rowland Jr. | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -53,475 | 0 | 09 Feb 2026 | Direct | ||
| Charles A. Rowland Jr. | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -24,366 | 0 | 09 Feb 2026 | Direct | ||
| Jason P. Rhodes | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -827,946 | 0 | 09 Feb 2026 | See Footnote | ||
| Jason P. Rhodes | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -20,120 | 0 | 09 Feb 2026 | Direct | ||
| Anthony G. Quinn | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -7,283 | 0 | 09 Feb 2026 | By Quinn Family Irrevocable Trust of 2021 | ||
| Anthony G. Quinn | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -29,928 | 0 | 09 Feb 2026 | Direct | ||
| Anthony G. Quinn | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -20,120 | 0 | 09 Feb 2026 | Direct | ||
| Donald William Nicholson | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -21,357 | 0 | 09 Feb 2026 | Direct | ||
| Donald William Nicholson | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -20,120 | 0 | 09 Feb 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -27,500 | 0 | 09 Feb 2026 | By 2020 Trust | ||
| Geoff Mcdonough | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -22,646 | 0 | 09 Feb 2026 | By 2018 Trust | ||
| Geoff Mcdonough | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -138,492 | 0 | 09 Feb 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -264,213 | 0 | 09 Feb 2026 | Direct | ||
| Jeffrey M. Jonas | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -24,366 | 0 | 09 Feb 2026 | Direct | ||
| Yalonda Howze | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -3,759 | 0 | 09 Feb 2026 | Direct | ||
| Yalonda Howze | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -55,325 | 0 | 09 Feb 2026 | Direct | ||
| Ronald Harold Wilfred Cooper | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -950 | 0 | 09 Feb 2026 | Direct | ||
| Ronald Harold Wilfred Cooper | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -16,420 | 0 | 09 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -2,072 | 0 | 09 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -56,045 | 0 | 09 Feb 2026 | Direct | ||
| Gustav Christensen | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -13,142 | 0 | 09 Feb 2026 | Direct | ||
| Gustav Christensen | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -20,120 | 0 | 09 Feb 2026 | Direct | ||
| Dannielle Appelhans | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -736 | 0 | 09 Feb 2026 | By Spouse | ||
| Dannielle Appelhans | GBIO | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -100% | -1,263 | 0 | 09 Feb 2026 | Direct | ||
| Dannielle Appelhans | GBIO | Stock Option (right to buy) | Disposed to Issuer | -100% | -15,340 | 0 | 09 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Common Stock | Tax liability | -3.36% | -72 | 2,072 | 02 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Common Stock | Options Exercise | 12.3% | 235 | 2,144 | 02 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Restricted Stock Units | Options Exercise | -100% | -235 | 0 | 02 Feb 2026 | Direct | ||
| Yalonda Howze | GBIO | Common Stock | Tax liability | -11.6% | -495 | 3,759 | 02 Feb 2026 | Direct | ||
| Yalonda Howze | GBIO | Common Stock | Options Exercise | 64.8% | 1,673 | 4,254 | 02 Feb 2026 | Direct | ||
| Yalonda Howze | GBIO | Restricted Stock Units | Options Exercise | -100% | -1,673 | 0 | 02 Feb 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Tax liability | -0.4% | -550 | 138,492 | 02 Feb 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Options Exercise | 1.15% | 1,582 | 139,042 | 02 Feb 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Restricted Stock Units | Options Exercise | -100% | -1,582 | 0 | 02 Feb 2026 | Direct | ||
| Kevin John Conway | GBIO | Common Stock | Tax liability | -0.88% | -17 | 1,909 | 15 Jan 2026 | Direct | ||
| Kevin John Conway | GBIO | Common Stock | Options Exercise | 3.16% | 59 | 1,926 | 15 Jan 2026 | Direct | ||
| Kevin John Conway | GBIO | Restricted Stock Units | Options Exercise | -20.1% | -59 | 235 | 15 Jan 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Tax liability | -0.1% | -137 | 137,460 | 15 Jan 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Options Exercise | 0.29% | 395 | 137,597 | 15 Jan 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Restricted Stock Units | Options Exercise | 33.3% | 395 | 1,582 | 15 Jan 2026 | Direct | ||
| Yalonda Howze | GBIO | Common Stock | Tax liability | -3.69% | -99 | 2,581 | 15 Jan 2026 | Direct | ||
| Yalonda Howze | GBIO | Common Stock | Options Exercise | 14.3% | 335 | 2,680 | 15 Jan 2026 | Direct | ||
| Yalonda Howze | GBIO | Restricted Stock Units | Options Exercise | -16.7% | -335 | 1,673 | 15 Jan 2026 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Tax liability | -0.21% | -293 | 137,202 | 31 Oct 2025 | Direct | ||
| Geoff Mcdonough | GBIO | Common Stock | Options Exercise | 0.48% | 659 | 137,495 | 31 Oct 2025 | Direct | ||
| Geoff Mcdonough | GBIO | Restricted Stock Units | Options Exercise | -25% | -659 | 1,977 | 31 Oct 2025 | Direct |
* An asterisk sign (*) next to the price indicates that the price is likely invalid.