Geoff Mcdonough Generation Bio Co. (GBIO) insider trading activity

Geoff Mcdonough is PRESIDENT AND CEO of Generation Bio Co.. Currently has a direct ownership of 136,836 shares of GBIO, which is worth approximately $853,856. The most recent transaction as insider was on Oct 15, 2025, when has been sold 155 shares (Common Stock) at a price of $6.71 per share, resulting in proceeds of $1,040. This information was disclosed in a Form 4 filing with the Securities and Exchange Commission (SEC).

Shares Held (Direct Ownership) 137K

89.97% 3M change

89.77% 12M change

Total Value Held $853,856

GEOFF MCDONOUGH Transaction History

Date	Transaction	Value	Shares Traded	Shares Held
Oct 15 2025	SELL Payment of exercise price or tax liability	$1,040 $6.71 p/Share	155 Reduced 0.11%	136,836 Common Stock
Oct 15 2025	BUY Exercise of conversion of derivative security	-	527 Added 0.38%	136,991 Common Stock
Jul 15 2025	SELL Payment of exercise price or tax liability	$665 $0.43 p/Share	1,548 Reduced 0.11%	1,364,648 Common Stock
Jul 15 2025	BUY Exercise of conversion of derivative security	-	5,273 Added 0.38%	1,366,196 Common Stock
Apr 15 2025	SELL Payment of exercise price or tax liability	$572 $0.37 p/Share	1,548 Reduced 0.11%	1,349,664 Common Stock
Apr 15 2025	BUY Exercise of conversion of derivative security	-	5,274 Added 0.39%	1,351,212 Common Stock
Jan 15 2025	SELL Payment of exercise price or tax liability	$1,626 $0.89 p/Share	1,828 Reduced 0.14%	1,345,938 Common Stock
Jan 15 2025	BUY Exercise of conversion of derivative security	-	5,274 Added 0.39%	1,347,766 Common Stock
Oct 15 2024	SELL Payment of exercise price or tax liability	$3,746 $2.42 p/Share	1,548 Reduced 0.12%	1,337,629 Common Stock
Oct 15 2024	BUY Exercise of conversion of derivative security	-	5,274 Added 0.39%	1,339,177 Common Stock
Jul 15 2024	SELL Payment of exercise price or tax liability	$4,535 $2.93 p/Share	1,548 Reduced 0.12%	1,333,903 Common Stock
Jul 15 2024	BUY Exercise of conversion of derivative security	-	5,274 Added 0.39%	1,335,451 Common Stock
Apr 15 2024	SELL Payment of exercise price or tax liability	$5,727 $3.7 p/Share	1,548 Reduced 0.12%	1,323,458 Common Stock
Apr 15 2024	BUY Exercise of conversion of derivative security	-	5,274 Added 0.4%	1,325,006 Common Stock
Jan 15 2024	SELL Payment of exercise price or tax liability	$29,473 $1.91 p/Share	15,431 Reduced 1.16%	1,319,732 Common Stock
Jan 15 2024	BUY Exercise of conversion of derivative security	-	44,531 Added 3.25%	1,327,042 Common Stock
Oct 15 2023	SELL Payment of exercise price or tax liability	$33,679 $3.24 p/Share	10,395 Reduced 0.8%	1,288,187 Common Stock
Oct 15 2023	BUY Exercise of conversion of derivative security	-	23,437 Added 1.77%	1,298,582 Common Stock
Jul 15 2023	SELL Payment of exercise price or tax liability	$37,978 $5.08 p/Share	7,476 Reduced 0.58%	1,275,145 Common Stock
Jul 15 2023	BUY Exercise of conversion of derivative security	-	23,437 Added 1.79%	1,282,621 Common Stock
Apr 15 2023	SELL Payment of exercise price or tax liability	$30,955 $4.5 p/Share	6,879 Reduced 0.54%	1,256,068 Common Stock
Apr 15 2023	BUY Exercise of conversion of derivative security	-	23,437 Added 1.82%	1,262,947 Common Stock
Jan 15 2023	SELL Payment of exercise price or tax liability	$41,422 $5.1 p/Share	8,122 Reduced 0.65%	1,239,510 Common Stock
Jan 15 2023	BUY Exercise of conversion of derivative security	-	23,438 Added 1.84%	1,247,632 Common Stock
Oct 15 2022	SELL Payment of exercise price or tax liability	$58,316 $5.61 p/Share	10,395 Reduced 0.84%	1,222,329 Common Stock

Also insider at

SURF

Surface Oncology, Inc. Healthcare

Director

THRD

Third Harmonic Bio, Inc. Healthcare

Geoff Mcdonough

PRESIDENT AND CEO

Cambridge, MA

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