Gossamer Bio, Inc. insider trading

Does following Gossamer Bio, Inc.’s insiders pay?

From June 3, 2019 to August 20, 2025, 14 insiders reported 23 open-market purchases and 24 sales not made under a pre-set plan in Gossamer Bio, Inc. Twelve months after each purchase was reported, the shares were −49.5% against the S&P 500 on average (median −43.2%), over 13 purchases with a full year of prices; 23% beat the index. After sales, the shares moved −57.9% against the index over 12 months (a negative figure means selling was the right call). That rests on fewer than 20 purchases, too few to read much into. Buying each purchase the day after it was reported, an equal amount each, held 12 months or until that insider reported a sale, would have turned $10,000 on June 4, 2019 into $1,206 by November 2, 2026, −24.9% a year. It held shares 46% of the time; the S&P 500 on those same days, with Treasury bills otherwise, made $23,411 (+12.2% a year), and held throughout $30,086 (+16.1%).

Moves are the shares’ return including dividends minus the S&P 500’s, from the close on the first trading day after each report; the number of trades with a finished 12-month window is in brackets. Green means the trade went the insider’s way (a purchase ahead of the index, a sale followed by the shares trailing it). A trade reported both by a director or officer and by a fund or company they are linked to counts once here, under the person. Purchases count only where the share price actually traded was at least $5. These figures describe what the shares did, not why anyone traded. Insiders across all companies.