BCIP Life Sciences Associates, LP 4

What Happened
Bain Capital Life Sciences Investors, LLC (part of the Bain Capital Life Sciences entities and a reported ~10% owner) purchased a pre‑funded warrant and accompanying Series A and Series B warrants, each exercisable for 1,463,000 shares of Rapid Micro Biosystems, Inc. (RPID). Each instrument was purchased for $1.945 on May 20, 2026; the three purchases together cost approximately $8.54 million. The filings are coded P (purchase), i.e., an acquisition of derivative instruments rather than an outright purchase of common stock.

Key Details

• Transaction date: May 20, 2026; Form 4 filed May 22, 2026 (filed timely).
• Instrument and size: Pre‑Funded Warrant (1,463,000 shares) + Series A Warrant (1,463,000) + Series B Warrant (1,463,000).
• Price paid: $1.945 per instrument; ~ $2.845535M per instrument; total ~ $8.5366M.
• Shares owned after transaction (direct holdings): Bain Capital Life Sciences Fund, L.P. (7,651,369) + BCIP Life Sciences Associates, LP (783,191) = 8,434,560 shares reported as held directly (footnote disclosure). The purchased warrants are derivative holdings that could convert into additional shares if exercised.
• Notable footnotes: Pre‑Funded Warrant does not expire. Exercise of the warrants is subject to a 9.99% beneficial‑ownership cap — the warrants cannot be exercised to the extent doing so would push the holder (with affiliates) above 9.99% of outstanding Class A common stock. Series A/B warrants may be exercisable for shares (or pre‑funded warrants in lieu thereof).
• Transaction code: P = Purchase (institutional acquisition, not an insider executive sale).

Context
This was an institutional, derivative purchase by a 10% shareholder group (Bain Capital Life Sciences entities). Because these are warrants/pre‑funded warrants rather than immediate common‑stock purchases, they do not increase voting shares until exercised and are subject to the stated ownership cap. Purchases by large institutional holders can signal planned future exposure, but they differ from an executive buying common stock directly.