Insider · SEC Form 4 filer
Brian Posner
Companies
Where they file as an insider
Dyne Therapeutics (DYN) Director Latest filing Oct 2, 2026
Arch Capital Group (ACGL) Director Latest filing Jun 3, 2026
Track record
Did their buys beat the typical stock?
Open-market buys9
Quarters checked 6 months later2
Beat the typical stock —
Quarters too new to check2
Too soon to tell. 2 quarters have finished so far. We show a record once 3 have.
Dyne Therapeutics (DYN) Bought Oct 2, 2026 · $40K · 2,500 shares Too new Too new. Its 6-month check uses prices as of Jun 30, 2027.
Dyne Therapeutics (DYN) Bought May 20–Jun 8, 2026 · $157K · 9,000 shares Too new Too new. Its 6-month check uses prices as of Dec 31, 2026.
Dyne Therapeutics (DYN) Bought Mar 6–30, 2026 · $118K · 7,000 shares Behind typical Mar 31, 2026 $18.13 → Sep 30, 2026 $16.11 · −11.1% (typical stock +1.7%)
Arch Capital Group (ACGL) Bought Aug 1, 2025 · $17.3K · 1,000 shares Beat typical Sep 30, 2025 $90.73 → Mar 31, 2026 $95.99 · +5.8% (typical stock −3.4%)
Each row is one stock in one quarter, however many buys it took. We take the stock's price at the end of that quarter and again 6 months later, and compare it with the typical stock over the same dates. Prices are quarter-end values from funds' 13F reports (the middle value across 3 or more funds), through Sep 30, 2026. Moves past 3 times up or down, mostly stock splits, are left out. How we tested this.
Past results. This is data, not advice.
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