undamentalytics Newsletter

Prime Medicine, Inc. insider trading

Every open-market purchase and sale by Prime Medicine, Inc.'s officers, directors and largest shareholders since November 4, 2021, and what the share price did next.

No open-market insider trades reported in the last five years.

Does following Prime Medicine, Inc.’s insiders pay?

From February 20, 2024 to August 5, 2025, 6 insiders reported 10 open-market purchases and 0 sales not made under a pre-set plan in Prime Medicine, Inc. Twelve months after each purchase was reported, the shares were −87.5% against the S&P 500 on average (median −87.5%), over 1 purchase with a full year of prices; 0% beat the index. 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 February 21, 2024 into $3,737 by November 2, 2026, −30.7% a year. It held shares 37% of the time; the S&P 500 on those same days, with Treasury bills otherwise, made $13,079 (+10.5% a year), and held throughout $15,712 (+18.3%).

$0$5.0k$10.0k$15.0k 202420252026 $15.7k$13.1k$3.7k
Copying Prime Medicine, Inc.'s insidersS&P 500, same days investedS&P 500, held throughout $10,000 copying every open-market purchase by Prime Medicine, Inc.'s insiders from February 21, 2024, before costs and taxes, marked weekly. Uninvested money earns the Treasury bill rate; the portfolio held shares 37% of the time.
Prime Medicine, Inc.: each insider's record
InsiderRolePurchases12 months after their purchasesBeat the S&P 500Sales12 months after their salesLatest report
Liu David R. 10% owner 4 — — 0 — July 1, 2025
Nelsen Robert Director 2 −87.5% (1) 0% 0 — August 1, 2025
Alphabet Inc. 10% owner 1 — — 0 — August 5, 2025
Brudnick Richard Chief Business Officer 1 — — 0 — May 22, 2025
Lee Ann L. Chief Technical Officer 1 — — 0 — May 22, 2025
Reine Allan Chief Executive Officer 1 — — 0 — May 22, 2025

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.

When several insiders traded Prime Medicine, Inc.

Months when 2 or more insiders became net buyers, or 3 or more net sellers, of Prime Medicine, Inc. in reports dated in the 91 days before the month end, and how the stock did against the S&P 500 from that month end. After the 1 buying crowd with six months of prices, it averaged −60.6% against the index. One company's history is too short to judge by; the test across every company is the better guide.

MonthCrowd3 months on, vs S&P 5006 months12 months
February 29, 20242 buying−27.9%−60.6%−89.4%

Colours show whether the crowd was right: green when buyers were followed by a rise above the index, or sellers by a fall below it. Total returns from the month end; past patterns are not a forecast.

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