[Form 4] Prime Medicine, Inc. Insider Trading Activity
Rhea-AI Filing Summary
Prime Medicine (PRME) – Form 4 insider transaction filed 08/01/2025. ARCH Venture entities, collectively 10% owners, disclosed a purchase of 3,030,300 common shares at $3.30 per share (approx. $10.0 million). The buyer of record is ARCH Venture Fund XII, L.P.
Post-transaction indirect holdings stand at:
- ARCH Venture Fund X, L.P.: 6,128,297 shares (unchanged)
- ARCH Venture Fund X Overage, L.P.: 6,128,297 shares (unchanged)
- ARCH Venture Fund XII, L.P.: 6,230,300 shares (up from zero disclosed in this filing)
Total indirect ownership across the reporting group rises to roughly 18.5 million shares. The filing is one of two joint reports; Robert Nelsen is filing separately for his direct holdings.
Key take-away: A sizable open-market purchase by a long-term venture backer at a depressed price signals increased confidence in PRME’s prospects and tightens insider alignment with public shareholders.
Positive
- None.
Negative
- None.
Insights
TL;DR Large venture fund bought 3.0 M PRME shares at $3.30, lifting insider stake to 18.5 M; bullish governance signal.
The ARCH Venture complex, already a 10%+ holder, added 3,030,300 shares via Fund XII for about $10 million. No dispositions were reported. Given PRME’s 52-week low near $3, the purchase suggests insiders see deep value and are willing to add liquidity. The acquisition raises group ownership to ~18.5 M shares, likely >15% of outstanding shares (exact float not in filing). Such concentrated ownership can both support the share price and influence strategic direction. Impact classified as positive because fresh capital came at market—no dilutive structure—and reinforces long-term commitment.
Insider Trade Summary
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Purchase | Common Stock | 3,030,300 | $3.30 | $10.00M |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
Footnotes (1)
- Represents shares held directly by ARCH Venture Fund X, L.P. ("ARCH X"). ARCH Venture Partners X, L.P. ("AVP X LP") is the sole general partner of ARCH X. Represents shares held directly by ARCH Venture Fund X Overage, L.P. ("ARCH X Overage"). ARCH Venture Partners X Overage, L.P. ("AVP X Overage LP") is the sole general partner of ARCH X Overage. ARCH Venture Partners X, LLC ("AVP X LLC") is the sole general partner of each of AVP X LP and AVP X Overage LP. Keith Crandell, Kristina Burow and Steven Gillis are members of the investment committee of AVP X LLC (the "AVP X Committee Members"). AVP X LP and AVP X Overage LP may be deemed to beneficially own the shares held by ARCH X and ARCH X Overage, respectively, AVP X LLC may be deemed to beneficially own the shares held by ARCH X and ARCH X Overage, and each of the AVP X Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH X and ARCH X Overage. AVP X LP, AVP X Overage LP, AVP X LLC, and the AVP X Committee Members each disclaim beneficial ownership except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that such shares are beneficially owned by them for Section 16 or any other purpose. Represents shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the general partner of AVP XII LP. Keith Crandell, Kristina Burow and Steven Gillis are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any.
