Rapid Micro Biosystems, Inc. Schedule 13G/A Amendment No. 2 discloses that certain Longitude entities and two affiliated individuals report shared beneficial ownership of 3,529,245 shares of Class A common stock, representing 8.6% of the class. The filing cites March 31, 2026 as the share count reference, with 41,267,511 shares outstanding reported in the issuer's proxy statement.
The reporting persons named include Longitude Capital Partners II, LLC, Longitude Venture Partners II, L.P., and individuals Patrick G. Enright and Juliet Tammenoms Bakker. The filing states these shares are held of record by LVPII and that LCPII, as general partner, and the two managing members may be deemed to share voting and dispositive power.
Positive
None.
Negative
None.
Insights
Institutional holders disclose shared control over an 8.6% stake reported as of March 31, 2026.
The filing lists 3,529,245 shares held of record by LVPII with shared voting and dispositive power attributed to LCPII and its managing members. This is a standard ownership disclosure under Schedule 13G/A attributing beneficial ownership across affiliated entities and individuals.
Key dependencies include the issuer's outstanding share count of 41,267,511 used to calculate 8.6%. Subsequent filings could update percentages if outstanding shares or holdings change; timing is tied to the March 31, 2026 reference in the proxy statement.
Report clarifies record ownership and attribution among fund, general partner, and managers.
The filing explains that LVPII holds the shares of record while LCPII, as general partner, and Messrs. Enright and Bakker may be deemed to share voting and dispositive power. The report includes the standard disclaimer of direct beneficial ownership by the reporting individuals except to the extent of any pecuniary interest.
Investor implications are factual: the excerpt quantifies holdings (3,529,245 shares) and the as of date anchor. Further changes will appear only in later amendments or separate filings.
Key Figures
Shares beneficially owned:3,529,245 sharesPercent of class:8.6%Shares outstanding (reference):41,267,511 shares
3 metrics
Shares beneficially owned3,529,245 sharesreported by Longitude entities and individuals
Percent of class8.6%of Class A common stock as computed from outstanding shares
Shares outstanding (reference)41,267,511 sharesoutstanding as of March 31, 2026 (proxy statement)
Key Terms
Schedule 13G/A, beneficial ownership, shared dispositive power, held of record
4 terms
Schedule 13G/Aregulatory
"Schedule 13G/A Amendment No. 2 appears on the cover"
A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.
beneficial ownershipfinancial
"Amount beneficially owned: See Row 9 of the cover page"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
shared dispositive powerfinancial
"Shared Dispositive Power 3,529,245.00 appears in the cover rows"
held of recordregulatory
"All such shares are held of record by LVPII appears in the comment"
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 2)
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)
03/31/2026
(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
Longitude Capital Partners II, 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
3,529,245.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,529,245.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,529,245.00
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)
8.6 %
12
Type of Reporting Person (See Instructions)
OO
Comment for Type of Reporting Person: All such shares are held of record by LVPII (as defined in the Explanatory Note below). LCPII (as defined in the Explanatory Note below) is the general partner of LVPII and may be deemed to have voting and dispositive power with respect to these securities. Patrick G. Enright and Juliet Tammenoms Bakker are the managing members of LCPII and may each be deemed to share voting and dispositive power with respect to these securities.
Based on 41,267,511 shares of Class A Common Stock, outstanding as of March 31, 2026, as reported by the Issuer in the definitive proxy statement on Schedule 14A, filed with the United States Securities and Exchange Commission (the Commission) on April 8, 2026 (the Proxy Statement).
SCHEDULE 13G
CUSIP Number(s):
75340L104
1
Names of Reporting Persons
Longitude Venture Partners II, L.P.
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
3,529,245.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,529,245.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,529,245.00
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)
8.6 %
12
Type of Reporting Person (See Instructions)
PN
Comment for Type of Reporting Person: All such shares are held of record by LVPII. LCPII is the general partner of LVPII and may be deemed to have voting and dispositive power with respect to these securities. Patrick G. Enright and Juliet Tammenoms Bakker are the managing members of LCPII and may each be deemed to share voting and dispositive power with respect to these securities.
Based on 41,267,511 shares of Class A Common Stock, outstanding as of March 31, 2026, as reported by the Issuer in the Proxy Statement.
SCHEDULE 13G
CUSIP Number(s):
75340L104
1
Names of Reporting Persons
Longitude Prime Partners, 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
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
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)
0 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
75340L104
1
Names of Reporting Persons
Longitude Prime Fund, L.P.
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
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
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)
0 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
75340L104
1
Names of Reporting Persons
Patrick G. Enright
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
3,529,245.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,529,245.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,529,245.00
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)
8.6 %
12
Type of Reporting Person (See Instructions)
IN
Comment for Type of Reporting Person: All such shares are held of record by LVPII. LCPII is the general partner of LVPII and may be deemed to have voting and dispositive power with respect to these securities. Patrick G. Enright and Juliet Tammenoms Bakker are the managing members of LCPII and may each be deemed to share voting and dispositive power with respect to these securities.
Based on 41,267,511 shares of Class A Common Stock, outstanding as of March 31, 2026, as reported by the Issuer in the Proxy Statement.
SCHEDULE 13G
CUSIP Number(s):
75340L104
1
Names of Reporting Persons
Juliet Tammenoms Bakker
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
3,529,245.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,529,245.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,529,245.00
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)
8.6 %
12
Type of Reporting Person (See Instructions)
IN
Comment for Type of Reporting Person: All such shares are held of record by LVPII. LCPII is the general partner of LVPII and may be deemed to have voting and dispositive power with respect to these securities. Patrick G. Enright and Juliet Tammenoms Bakker are the managing members of LCPII and may each be deemed to share voting and dispositive power with respect to these securities.
Based on 41,267,511 shares of Class A Common Stock, outstanding as of March 31, 2026, as reported by the Issuer in the Proxy Statement.
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:
Explanatory Note:
This Amendment No. 2 ("Amendment No. 2") amends and supplements the Schedule 13G initially filed with the Commission on February 15, 2022, as amended by Amendment No. 1 filed with the Commission on February 14, 2023 (the "Original Schedule 13G") and is being filed by Longitude Capital Partners II, LLC ("LCPII"), Longitude Venture Partners II, L.P. ("LVPII"), Longitude Prime Partners, LLC ("LPP") and Longitude Prime Fund, L.P. ("LPF" and together with LCPII, LVPII and LPP, the "Reporting Entities") and Patrick G. Enright and Juliet Tammenoms Bakker (together, the "Reporting Individuals"). The Reporting Entities and the Reporting Individuals are collectively referred to as the "Reporting Persons." The agreement among the Reporting Persons to file jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act is filed as Exhibit 1 to the Original Schedule 13G. Only those items that are hereby reported are amended; all other items reported in the Original Schedule 13G remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment No. 2 have the meanings ascribed to them in the Original Schedule 13G.
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each Reporting Person is 2740 Sand Hill Road, 2nd Floor, Menlo Park, CA 94025.
(c)
Citizenship:
Each of LCPII and LPP is a limited liability company organized under the laws of the State of Delaware. Each of LVPII and LPF is a limited partnership organized under the laws of the State of Delaware. Each of the Reporting Individuals is a citizen of the United States of America.
(d)
Title of class of securities:
Class A common stock, $0.01 par value per share
(e)
CUSIP No.:
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:
See Row 9 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
(b)
Percent of class:
See Row 11 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
See Row 5 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
(ii) Shared power to vote or to direct the vote:
See Row 6 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
(iii) Sole power to dispose or to direct the disposition of:
See Row 7 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
(iv) Shared power to dispose or to direct the disposition of:
See Row 8 of the cover page for each Reporting Person and the corresponding footnotes. Except to the extent of his, her or its pecuniary interest therein, each Reporting Person disclaims beneficial ownership of such shares of Class A Common Stock, except for the shares, if any, such Reporting Person holds of record.
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.
Under certain circumstances set forth in the limited partnership agreements of each of LVPII and LPF and the limited liability company agreement of each of LCPII and LPP, the general and limited partners or members, as the case may be, of each of such entities may be deemed to have the right to receive dividends from, or the proceeds from, the sale of securities of the Issuer owned by each such entity of which they are a partner or member, as the case may be.
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:
Not Applicable
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.
Longitude Capital Partners II, LLC
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, Authorized Signatory
Date:
05/15/2026
Longitude Venture Partners II, L.P.
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, Authorized Signatory
Date:
05/15/2026
Longitude Prime Partners, LLC
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, Authorized Signatory
Date:
05/15/2026
Longitude Prime Fund, L.P.
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, Authorized Signatory
Date:
05/15/2026
Patrick G. Enright
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, as attorney-in-fact for Patrick G. Enright
Date:
05/15/2026
Juliet Tammenoms Bakker
Signature:
/s/ Cristiana Blauth Oliveira
Name/Title:
Cristiana Blauth Oliveira, as attorney-in-fact for Juliet Tammenoms Bakker
What stake does Longitude report in Rapid Micro Biosystems (RPID)?
The filing reports 3,529,245 shares, equal to 8.6% of Class A common stock. This percentage uses 41,267,511 shares outstanding as of March 31, 2026, per the issuer's proxy statement.
Who are the named reporting persons in the 13G/A?
Longitude Capital Partners II, LLC, Longitude Venture Partners II, L.P., and individuals Patrick G. Enright and Juliet Tammenoms Bakker are listed as reporting persons in the amendment.
Are the shares held directly by the individuals named?
No. The filing states the shares are held of record by LVPII and that LCPII (general partner) and the managing members may be deemed to share voting and dispositive power. Each person disclaims beneficial ownership except for any shares held of record.
What date is used to compute the 8.6% ownership figure?
The percentage is computed based on 41,267,511 shares outstanding as of March 31, 2026, as reported by the issuer in its definitive proxy statement filed April 8, 2026.
Does the filing indicate any change in holdings or transactions?
The amendment provides an ownership snapshot attributing shared voting and dispositive power; it does not disclose purchases or sales in this excerpt. Future amendments would report transactional changes if they occur.
