Rapid Micro CFO sells shares for tax withholding

Rapid Micro Biosystems chief financial officer Sean M. Wirtjes reported an automatic sale of shares to cover taxes tied to equity compensation.

Accepted by SEC EDGAR 02/10/2026 - 06:54 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

Rapid Micro Biosystems chief financial officer Sean M. Wirtjes reported an automatic sale of shares to cover taxes tied to equity compensation. On February 9, 2026, he sold 6,027 shares of Class A common stock at $3.7827 per share in a transaction coded as a sale. The filing states this sale was made automatically to satisfy tax obligations arising from the vesting of restricted stock units. After this transaction, Wirtjes directly owned 483,928 shares of Rapid Micro Biosystems Class A common stock.

Insider Trade Summary

Net Seller: 6,027 shares

Net Sell 1 txn

Insider WIRTJES SEAN M

Role CHIEF FINANCIAL OFFICER

Sold 6,027 shs ($23K)

Type	Security	Shares	Price	Value
Sale	Class A Common Stock	6,027	$3.7827	$23K

Holdings After Transaction: Class A Common Stock — 483,928 shares (Direct)

Footnotes (1)

1. F1. Represents the automatic sale of stock to cover the associated tax obligations with the vesting of restricted stock units.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Rapid Micro Biosystems (RPID) report in this Form 4?

Rapid Micro Biosystems reported a share sale by its CFO. Chief financial officer Sean M. Wirtjes sold 6,027 shares of Class A common stock on February 9, 2026, in an automatic transaction related to restricted stock unit vesting.

How many Rapid Micro Biosystems (RPID) shares did the CFO sell and at what price?

The CFO sold 6,027 shares at $3.7827 each. The transaction involved Class A common stock and was reported as a sale, providing a clear record of the number of shares and the per-share price involved.

Why did the Rapid Micro Biosystems (RPID) CFO sell 6,027 shares?

The sale was to cover tax obligations on vesting RSUs. The filing explains that the 6,027 shares were automatically sold to satisfy taxes associated with the vesting of restricted stock units granted to the chief financial officer.

How many Rapid Micro Biosystems (RPID) shares does the CFO own after the sale?

After the transaction, the CFO directly owned 483,928 shares. The Form 4 shows Sean M. Wirtjes’ beneficial ownership in Class A common stock following the automatic tax-related sale of 6,027 shares.

Is the Rapid Micro Biosystems (RPID) insider transaction direct or indirect ownership?

The reported holdings are directly owned by the CFO. The filing lists the ownership form as “D” for direct, with no indication of indirect ownership through entities such as trusts, partnerships, or family investment vehicles.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

WIRTJES SEAN M

(Last) (First) (Middle)

C/O RAPID MICRO BIOSYSTEMS, INC.

25 HARTWELL AVENUE

(Street)

LEXINGTON MA 02421

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
RAPID MICRO BIOSYSTEMS, INC. [ RPID ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CHIEF FINANCIAL OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
02/09/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	02/09/2026		S		6,027(1)	D	$3.7827	483,928	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents the automatic sale of stock to cover the associated tax obligations with the vesting of restricted stock units.

Remarks:

	/s/ Sean M. Wirtjes	02/10/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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