Thayer Ventures Acquisition Corp II

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM

10-K

For the fiscal year ended December 31,2025

For the transition period from

to

Commission File

No.001-42641

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code:

(415)782-1414

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

Securities registered pursuant to Section 12(g) of the Securities Exchange 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 Securities Exchange 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 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. (Check one):

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 Exchange Act). Yes☒ No ☐

The registrant’s units began trading on The Nasdaq Capital Market on May 15, 2025 and the registrant’s Class A ordinary shares began separate trading on the Nasdaq Capital Market on July 2, 2025. The aggregate market value of the registrant’s Class A ordinary shares outstanding, other than shares held by persons who may be deemed affiliates of the registrant, on June 30, 2025, computed by reference to the closing price for the Class A ordinary shares of the registrant on such date, as reported on the Nasdaq Capital Market, was $139,169,586.70.

As of

March 30, 2026, the

Registrant had 20,487,500 Class A Ordinary Shares, par value $0.0001 per share, and 6,708,333 Class B Ordinary Shares, par value $0.0001 per share, of the registrant issued and outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

None.