Bain Capital GSS Sponsor discloses 21.18% BCSS ownership

Rhea-AI Filing Summary

Bain Capital GSS Investment Sponsor LLC filed a Schedule 13G reporting beneficial ownership of 12,370,000 Class A Ordinary Shares of Bain Capital GSS Investment Corp. (BCSS), representing 21.18% of the class as of the event date 10/01/2025. The reporting person has sole voting and sole dispositive power over all 12,370,000 shares.

The stake includes 11,470,000 Class B founder shares that are automatically convertible into Class A as described in the issuer’s Form S-1, and 900,000 private placement units that include 900,000 Class A shares. The reporting person is organized in the Cayman Islands.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Bain Capital GSS Investment Corp.

(Name of Issuer)

Class A Ordinary Shares, $0.0001 par value

(Title of Class of Securities)

G0R78B106

(CUSIP Number)

10/01/2025

(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)

SCHEDULE 13G

CUSIP No. G0R78B106

1

Names of Reporting Persons

Bain Capital GSS Investment Sponsor 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

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 12,370,000.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 12,370,000.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

12,370,000.00

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)

21.18 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: (1) See Item 4 below. The Reporting Person owns 11,470,000 Class B Ordinary Shares of the Issuer, which are automatically convertible into the Issuer's Class A Ordinary Shares as more fully described under the heading "Description of Securities-Founder Shares" in the Issuer's registration statement on Form S-1 (File No. 333-290126) (the "Registration Statement"). The Reporting Person also owns 900,000 private placement units, which include 900,000 Class A Ordinary shares referred to as private placement shares in the Registration Statement.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Bain Capital GSS Investment Corp.
(b)	Address of issuer's principal executive offices: 200 Clarendon Street, Boston, Massachusetts 02116
Item 2.
(a)	Name of person filing: Bain Capital GSS Investment Sponsor LLC (the "Reporting Person")
(b)	Address or principal business office or, if none, residence: 200 Clarendon Street, Boston, Massachusetts 02116
(c)	Citizenship: Cayman Islands
(d)	Title of class of securities: Class A Ordinary Shares, $0.0001 par value
(e)	CUSIP No.: G0R78B106
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: 12,370,000
(b)	Percent of class: 21.18%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 12,370,000
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 12,370,000
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
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.

Bain Capital GSS Investment Sponsor LLC

Signature:	/s/ Angelo Rufino
Name/Title:	Authorized Signatory
Date:	10/15/2025

FAQ

What percentage of BCSS does the sponsor report owning?

The filing reports 21.18% beneficial ownership of BCSS Class A Ordinary Shares.

How many BCSS shares are reported as beneficially owned?

The sponsor reports 12,370,000 Class A Ordinary Shares beneficially owned.

What makes up the 12,370,000 shares reported by the sponsor?

It includes 11,470,000 Class B founder shares (convertible into Class A) and 900,000 private placement units that include 900,000 Class A shares.

Does the sponsor have sole or shared voting power over BCSS shares?

The sponsor reports sole voting power: 12,370,000 and shared voting power: 0.

What is the event date for this Schedule 13G?

The event date triggering the filing is 10/01/2025.

Where is the reporting person organized?

The reporting person, Bain Capital GSS Investment Sponsor LLC, is organized in the Cayman Islands.