PRME SCHEDULE 13D/A: SEC filing

ARCH Venture Fund entities

Filed with the SEC on Nov 13, 2026 · accession 0001193125-26-460600

PRME filed a SCHEDULE 13D/A (schedule 13d/a) with the SEC on Nov 13, 2026. ARCH Venture Fund entities filed an amended Schedule 13D disclosing beneficial ownership of approximately 18,486,894 shares, or 8.3%, of Prime Medicine's common stock following the company's November 2026 underwritten offering. The stock moved +9.8% by the first close after the filing.

Summary of the filing

ARCH Venture Fund entities filed an amended Schedule 13D disclosing beneficial ownership of approximately 18,486,894 shares, or 8.3%, of Prime Medicine's common stock following the company's November 2026 underwritten offering. No transactions in the stock were effected by the reporting persons in the last 60 days.

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Key details

Total shares beneficially owned by ARCH reporting persons$18.5M

Shares of common stock outstanding used for percentage calculation$223.0M

Shares sold by issuer in November 2026 underwritten offering$41.1M

Vested options held by Robert Nelsen$139K

Issuer/subject companyPrime Medicine, Inc.

Reporting person; record holder of 6,230,300 sharesARCH Venture Fund XII, L.P.

Reporting person; record holder of 6,128,297 sharesARCH Venture Fund X, L.P.

Reporting person; record holder of 6,128,297 sharesARCH Venture Fund X Overage, L.P.

Managing director, arch venture partnersRobert Nelsen

Managing director, arch venture partnersKeith Crandell

Managing director, arch venture partnersKristina Burow

Managing director, arch venture partnersSteven Gillis

Attorney-in-factMark McDonnell

How PRME stock reacted

Close before

$3.89

Nov 12, 2026

First close after

+9.77%

$4.27

5 trading days

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Since filing

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Frequently asked questions

What did PRME file with the SEC on Nov 13, 2026?

PRME filed a SCHEDULE 13D/A (SEC filing). ARCH Venture Fund entities filed an amended Schedule 13D disclosing beneficial ownership of approximately 18,486,894 shares, or 8.3%, of Prime Medicine's common stock following the company's November 2026 underwritten offering. No transactions in the stock were effected by the reporting persons in the last 60 days.

How do I read a SCHEDULE 13D/A?

A report the company filed with the SEC (the US market regulator). Start with the summary, then the key amounts and names. Compare it with the company’s earlier filings.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A SCHEDULE 13D/A (schedule 13d/a): A report the company filed with the SEC (the US market regulator).

How did PRME stock react to this filing?

PRME closed at $3.89 before the filing and $4.27 on Nov 13, 2026 (+9.77%).

Other PRME SEC filings

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