United States

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 8-K

Current Report

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 13, 2026

COLLECTIVE ACQUISITION CORP.

(Exact name of registrant as specified in its charter)

12955 Biscayne Boulevard Suite 200 PMB 616

Miami, FL 33181

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (561) 489-2062

DUNE ACQUISITION CORPORATION II

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

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

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

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. ☐

Item 3.02 Unregistered Sales of Equity Securities.

On August 13, 2026, Collective Acquisition Corp., a Cayman Islands exempted company (the “Company”), issued an aggregate of 3,500,000 Class A Ordinary Shares to Collective Acquisition Sponsor LLC (the “Sponsor”), upon the conversion (the “Conversion”) of an equal number of Class B Ordinary Shares held by the Sponsor. The Class A Ordinary Shares issued in connection with the Conversion are subject to the same restrictions applicable to the Class B Ordinary Shares prior to the Conversion, including certain transfer restrictions, waiver of redemption rights and the obligation to vote in favor of a Business Combination as described in the final prospectus filed with the Securities and Exchange Commission by the Company on May 8, 2025, in connection with the Company’s initial public offering. No consideration was paid in connection with the Conversion. Following the Conversion, there are 5,119,501 Class A Ordinary Shares issued and outstanding and 2,250,000 Class B Ordinary Shares issued and outstanding.

The Class A Ordinary Shares issued upon the Conversion have not been registered under the Securities Act of 1933, as amended, in reliance on the exemption from registration provided by Section 3(a)(9) thereof.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.