Bain Capital GSS Investment Corp.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the period from March 24, 2025 (inception) through December 31,2025

OR

For the transition period from

to

.

Commission File Number

001-42874

Bain Capital GSS Investment Corp.

(Exact Name of Registrant as Specified in Its Charter)

Registrant’s telephone number, including area code:+1

617-516-2000

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the

Securities

Act. Yes ☐No ☒

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. Yes ☐No ☒

Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days Yes ☒ No ☐

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation

S-T

(§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a

non-accelerated

filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in

Rule 12b-2

of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to

§240.10D-1(b). ☐

Indicate by check mark whether the Registrant is a shell company (as defined in Rule

12b-2

of the Act). Yes☒ No ☐

As of June 30, 2025 (the last business day of the registrant’s second fiscal quarter), the registrant’s securities werenot publicly traded. The registrant’s units (the “Units”) began trading on the New York Stock Exchange (“NYSE”) on September 30, 2025 and the registrant’s Class A ordinary shares, par value $0.0001 (the “Class A ordinary shares”) and warrants included in the Units began separate trading on Nasdaq on November 20, 2025 at the option of the holders thereof. The aggregate market value of the ordinary shares (as defined below) issued and outstanding, other than shares held by persons who may be deemed affiliates of the registrant, computed by reference to the $10.08 closing sales price for the ordinary shares on December 31, 2025, as reported on the NYSE, was approximately $472.8 million..

As of March

, 2026, there were

46,900,000

Class A ordinary shares, $

0.0001

par

value and 11,500,000 Class B ordinary shares, $0.0001 par value, issued and outstanding.

ANNUAL REPORT ON FORM 10-K

TABLE OF CONTENTS

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