WIRTJES SEAN M 4

What Happened Sean M. Wirtjes, Chief Financial Officer of Rapid Micro Biosystems (RPID), reported a sale of 7,480 shares on 2026-03-11 at $4.32 per share, totaling approximately $32,299. The sale is reported as a disposition (code S) and was executed to satisfy tax withholding obligations tied to the vesting of restricted stock units (RSUs), per the filing footnote.

Key Details

• Transaction date and price: 2026-03-11 — 7,480 shares at $4.32 each (total ≈ $32,299).
• Transaction type: Sale (code S) reported as open market or private sale.
• Footnote: F1 — automatic sale to cover tax withholding on vested RSUs.
• Shares owned after transaction: Not disclosed in this filing.
• Filing date/timeliness: Form 4 filed 2026-03-12 (filed the next day; appears timely under SEC reporting rules).

Context This was a tax-withholding sale related to RSU vesting, a routine administrative transaction common for insiders when equity awards vest. Such sales generally reflect tax obligations rather than a directional bet on the company. The filing does not indicate a 10b5-1 plan or other trading arrangement.