[Form 4] RAPID MICRO BIOSYSTEMS, INC. Insider Trading Activity

Rhea-AI Filing Summary

Rapid Micro Biosystems (RPID) reported insider transactions by President & CEO and Director Robert G. Spignesi, Jr. on 10/17/2025. He exercised stock options (code M) for 3,400 and 7,833 shares at an exercise price of $0.75 per share via net exercise. The company withheld 2,072 and 4,774 shares (code F) using the $3.08 closing price to cover the exercise price and taxes, consistent with the 2010 Stock Option and Grant Plan. Following these transactions, he directly owned 974,937 Class A common shares.

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

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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^*

Spignesi Robert G. Jr.

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	PRESIDENT AND CEO

3. Date of Earliest Transaction (Month/Day/Year)
10/17/2025

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	10/17/2025		M		3,400	A	$0.75	973,950	D
Class A Common Stock	10/17/2025		F		2,072(1)	D	$3.08	971,878	D
Class A Common Stock	10/17/2025		M		7,833	A	$0.75	979,711	D
Class A Common Stock	10/17/2025		F		4,774(2)	D	$3.08	974,937	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
Stock Option (Right to Buy)	$0.75	10/17/2025		M			3,400	(3)	10/22/2025	Class A Common Stock	3,400	$0	0	D
Stock Option (Right to Buy)	$0.75	10/17/2025		M			7,833	(3)	10/22/2025	Class A Common Stock	7,833	$0	0	D

Explanation of Responses:

1. Represents a "net exercise" of outstanding stock options. The reporting person received 1,328 shares of common stock on net exercise of option to purchase 3,400 shares of common stock. The Company withheld 2,072 shares of common stock underlying the option for payment of the exercise price and tax withholdings, using the closing stock price on October 17, 2025 of $3.08, pursuant to the terms of the 2010 Stock Option and Grant Plan.

2. Represents a "net exercise" of outstanding stock options. The reporting person received 3,059 shares of common stock on net exercise of option to purchase 7,833 shares of common stock. The Company withheld 4,774 shares of common stock underlying the option for payment of the exercise price and tax withholdings, using the closing stock price on October 17, 2025 of $3.08, pursuant to the terms of the 2010 Stock Option and Grant Plan.

3. The option is fully vested and exercisable.

Remarks:

	/s/ Sean M. Wirtjes, Attorney-in-Fact for Robert G. Spignesi, Jr.	10/21/2025
	** 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did RPID’s CEO report on Form 4?

He executed two option exercises (code M) for 3,400 and 7,833 shares at $0.75 on 10/17/2025, with share withholding for taxes and exercise price.

How many shares were withheld to cover costs?

The company withheld 2,072 and 4,774 shares (code F) using the $3.08 closing price on 10/17/2025.

How many shares does the CEO own after these transactions?

He directly owned 974,937 shares of Class A common stock following the reported transactions.

What is the exercise price of the options?

The stock options carried an exercise price of $0.75 per share.

Were the options vested?

Yes. The filing states the option is fully vested and exercisable.

What pricing was used for withholding shares?

The $3.08 closing stock price on 10/17/2025 was used for payment of the exercise price and tax withholdings.

What is the reporting person’s role at RPID?

Robert G. Spignesi, Jr. is President & CEO and a Director.