[Form 4] Rapid Micro Biosystems, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Rapid Micro Biosystems, Inc. (RPID) – CEO Form 4 filing dated 10 Jul 2025

President & CEO Robert G. Spignesi Jr. reported a series of transactions from 8-10 Jul 2025 involving performance-based restricted stock units (PRSUs):

• Vesting/Exercise (Code M): 75,433 Class A shares were issued at a $0 exercise price after performance criteria were met (25,144 on 7/08, 25,144 on 7/09, 25,145 on 7/10).
• Tax-related sales (Code S): 33,688 shares were sold to cover withholding obligations at prices between $3.398-$3.513.
• Net share increase: The CEO’s direct holdings rose by approximately 41,745 shares to 944,015 shares after the transactions. This total includes 29,904 shares previously purchased under the company’s employee stock purchase plan (3/14/2025).

No derivative securities remain outstanding from these transactions. Because the sales were explicitly to satisfy tax obligations, the actions are generally viewed as neutral to modestly positive—they do not signal discretionary selling pressure, while the net increase modestly aligns the CEO’s interests with shareholders.

Insights

Securities Analyst

TL;DR: CEO netted +41.7k shares via PRSU vesting; sales only for taxes, signalling neutral-to-slightly positive alignment, low market impact.

The filing shows standard PRSU settlement. Although the dollar value sold (≈$117k) may appear as insider selling, Form 4 footnotes clarify it was solely for tax withholding—a routine mechanism that avoids out-of-pocket cash payments by the executive. The resultant 944k-share stake represents material personal exposure and marginally increases the CEO’s ownership stake. Because no open-market purchases occurred and the stock issuance was compensation-related, the signal is not as strong as voluntary buying. Impact on valuation or sentiment is therefore limited.

Corporate Governance Specialist

TL;DR: Routine equity-based compensation vesting; ownership now ~944k shares, reinforcing alignment but offering little incremental governance insight.

Performance RSU vesting indicates management met previously set KPIs, a potential positive for compensation design integrity. The CEO chose the common tax-sell-to-cover route, avoiding excessive discretionary sales. No red flags—no 10b5-1 plan usage, no derivative hedging, and no joint filings. Overall governance implications are neutral; shareholders may note growing insider ownership but should not over-interpret the event.

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

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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)
07/08/2025

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	07/08/2025		M		25,144(1)	A	$0	897,510	D
Class A Common Stock	07/08/2025		S		10,824(2)	D	$3.5127	886,686	D
Class A Common Stock	07/09/2025		M		25,144(1)	A	$0	911,830	D
Class A Common Stock	07/09/2025		S		11,247(2)	D	$3.5103	900,583	D
Class A Common Stock	07/10/2025		M		25,145(1)	A	$0	925,728	D
Class A Common Stock	07/10/2025		S		11,617(2)	D	$3.398	944,015(3)	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. Shares were acquired upon satisfaction of performance criteria underlying previously granted performance restricted stock units.

2. The sales reported on this Form 4 represent shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting and settlement of performance restricted stock units.

3. Includes 29,904 shares acquired under the Rapid Micro Biosystems, Inc. employee stock purchase plan on March 14, 2025.

Remarks:

	/s/ Sean M. Wirtjes, Attorney-in-Fact for Robert G. Spignesi, Jr.	07/10/2025
	** 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.
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FAQ

How many RPID shares did CEO Robert Spignesi acquire on 8-10 July 2025?

He acquired 75,433 shares via PRSU vesting over the three-day period.

Why did the CEO sell RPID shares immediately after vesting?

Form 4 footnotes state the 33,688 shares were sold solely to cover tax withholding obligations.

What is Robert Spignesi’s total direct ownership after the transactions?

His direct stake increased to 944,015 Class A shares.

At what prices were the RPID shares sold?

Shares were sold between $3.398 and $3.5127 per share.

Do these transactions affect Rapid Micro Biosystems’ financials?

No; Form 4 filings report insider activity and do not directly impact the company’s financial statements.

Were any derivative securities (options, warrants) involved?

No derivative positions remain; only underlying common shares were involved in this filing.