Armistice Capital (RPID) discloses 3.33M-share position in Rapid Micro Biosystems

Rhea-AI Filing Summary

Rapid Micro Biosystems, Inc. has a significant shareholder position reported by Armistice Capital, LLC and Steven Boyd. The reporting group beneficially owns 3,328,000 shares of Class A common stock, representing 7.29% of the class. All voting and dispositive authority over these shares is reported as shared, with no sole power to vote or dispose. The shares are directly held by Armistice Capital Master Fund Ltd., for which Armistice Capital serves as investment manager under an Investment Management Agreement, and Steven Boyd is the managing member of Armistice Capital. The Master Fund has the right to receive dividends and sale proceeds from the reported securities.

Key Figures

Beneficially owned shares: 3,328,000 shares Percent of class: 7.29% Shared voting power: 3,328,000 shares +3 more

6 metrics

Beneficially owned shares 3,328,000 shares Class A common stock reported by Armistice Capital and Steven Boyd

Percent of class 7.29% Ownership percentage of Rapid Micro Biosystems Class A common stock

Shared voting power 3,328,000 shares Shares over which the reporting persons share voting power

Shared dispositive power 3,328,000 shares Shares over which the reporting persons share dispositive power

Sole voting power 0 shares Shares over which the reporting persons have sole voting power

Sole dispositive power 0 shares Shares over which the reporting persons have sole dispositive power

Key Terms

beneficially own, shared voting power, shared dispositive power, Investment Management Agreement, +1 more

5 terms

beneficially own financial

"thus may be deemed to beneficially own the securities of the Issuer"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

shared voting power financial

"Shared Voting Power 3,328,000.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 3,328,000.00"

Investment Management Agreement financial

"pursuant to an Investment Management Agreement, Armistice Capital exercises voting"

An investment management agreement is a written contract that hires a professional to make buying, selling and strategy decisions for an investment account or fund, and sets out their duties, fees, risk limits, performance measures and reporting requirements. It matters to investors because the agreement determines who controls the money, how much the service costs, what risks are allowed, and how success or failure is measured—think of it as the service contract that defines expectations and remedies for a hired portfolio manager.

exempted company financial

"The Master Fund, a Cayman Islands exempted company that is an investment"

FAQ

How much of Rapid Micro Biosystems (RPID) does Armistice Capital beneficially own?

Armistice Capital and Steven Boyd beneficially own 3,328,000 shares of Rapid Micro Biosystems Class A common stock, representing 7.29% of the outstanding class, according to the Schedule 13G filing.

What voting power does Armistice Capital have over RPID shares?

The filing reports 0 shares with sole voting power and 3,328,000 shares with shared voting power. All voting authority over the Rapid Micro Biosystems shares is shared rather than held solely.

Who directly holds the Rapid Micro Biosystems (RPID) shares reported by Armistice Capital?

The 3,328,000 shares are directly held by Armistice Capital Master Fund Ltd.. Armistice Capital is the fund’s investment manager and exercises voting and investment power under an Investment Management Agreement.

What economic rights does the Master Fund have in RPID shares?

Armistice Capital Master Fund Ltd. has the right to receive dividends and proceeds from the sale of the reported Rapid Micro Biosystems securities, as disclosed under the more-than-5-percent ownership section.

How is Steven Boyd related to Armistice Capital’s stake in Rapid Micro Biosystems (RPID)?

Steven Boyd is the managing member of Armistice Capital, LLC and may be deemed to beneficially own the Rapid Micro Biosystems shares held by the Master Fund through his control of Armistice Capital.

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

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Available on EDGAR 08/14/2026 - 10:26 AM Accepted by SEC EDGAR 08/14/2026 - 10:25 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Rapid Micro Biosystems, Inc.

(Name of Issuer)

Class A common stock, $0.01 par value per share

(Title of Class of Securities)

75340L104

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 75340L104

1

Names of Reporting Persons

Armistice Capital, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,328,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,328,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,328,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

7.29 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP Number(s): 75340L104

1

Names of Reporting Persons

Steven Boyd

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,328,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,328,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,328,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

7.29 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Rapid Micro Biosystems, Inc.
(b)	Address of issuer's principal executive offices: 25 Hartwell Avenue, Lexington, MA 02421
Item 2.
(a)	Name of person filing: Armistice Capital, LLC Steven Boyd Collectively, the "Reporting Persons"
(b)	Address or principal business office or, if none, residence: Armistice Capital, LLC 510 Madison Avenue, 7th Floor New York, New York 10022 United States of America Steven Boyd c/o Armistice Capital, LLC 510 Madison Avenue, 7th Floor New York, New York 10022 United States of America
(c)	Citizenship: Armistice Capital, LLC - Delaware; Steven Boyd - United States of America
(d)	Title of class of securities: Class A common stock, $0.01 par value per share
(e)	CUSIP Number(s): 75340L104
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 3,328,000
(b)	Percent of class: 7.29%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 3,328,000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 3,328,000 Armistice Capital, LLC ("Armistice Capital") is the investment manager of Armistice Capital Master Fund Ltd. (the "Master Fund"), the direct holder of the Shares, and pursuant to an Investment Management Agreement, Armistice Capital exercises voting and investment power over the securities of the Issuer held by the Master Fund and thus may be deemed to beneficially own the securities of the Issuer held by the Master Fund. Mr. Boyd, as the managing member of Armistice Capital, may be deemed to beneficially own the securities of the Issuer held by the Master Fund. The Master Fund specifically disclaims beneficial ownership of the securities of the Issuer directly held by it by virtue of its inability to vote or dispose of such securities as a result of its Investment Management Agreement with Armistice Capital.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Master Fund, a Cayman Islands exempted company that is an investment advisory client of Armistice Capital, has the right to receive dividends from, or the proceeds from the sale of, the reported securities.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Armistice Capital, LLC

Signature:	/s/ Steven Boyd
Name/Title:	Steven Boyd - Managing Member
Date:	08/14/2026

Steven Boyd

Signature:	/s/ Steven Boyd
Name/Title:	Steven Boyd
Date:	08/14/2026

Exhibit Information

JOINT FILING STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on Schedule 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate. Dated: August 14, 2026 Armistice Capital, LLC By: /s/ Steven Boyd Steven Boyd - Managing Member Steven Boyd By: /s/ Steven Boyd