Dune Acquisition Corp II

DUNE ACQUISITION CORPORATION II

INFORMATION STATEMENT PURSUANT TO SECTION 14(f) OF

THE SECURITIES EXCHANGE ACT OF 1934 AND RULE 14f-1 THEREUNDER

NOTICE OF CHANGE IN THE COMPOSITION

OF THE BOARD OF DIRECTORS

This information statement is being furnished to holders of record of Dune Acquisition Corporation II, which we refer to as “we”, “us”, “our” or the “Company”, at the close of business on March 12, 2026 in accordance with the requirements of Section 14(f) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 14f-1 promulgated under the Exchange Act.

As of March 12, 2026, the Company had issued and outstanding 20,232,813 ordinary shares, consisting of 14,482,813 Class A ordinary shares, par value $0.0001 per share (“Class A Shares”) and 5,750,000 Class B ordinary shares, $0.0001 par value per share (“Class B Shares,” and together with the Class A Shares the “Ordinary Shares”). These are the Company’s only voting securities that would be entitled to vote for directors at a meeting if one were to be held. Each ordinary share is entitled to one vote.

No vote or other action by the Company’s shareholders is required in response to this information statement. Proxies are not being solicited in respect of the change of directors set forth in this information statement.

On January 30, 2026, Collective Acquisition Sponsor LLC, a Delaware limited liability company (the “New Sponsor”), the Company, Dune Acquisition Holdings II LLC, a Delaware limited liability company (the “Old Sponsor”), Carter Glatt, as the managing member of the Old Sponsor (the “Sponsor Member”), certain members of the Sponsor Member named as signatories thereto (the “Non-Managing Members”) and certain other institutional investors signatories thereto (the “Non-Managing Investors”, together with the Non-Managing Members and the Sponsor Member, the “Old Sponsor Members”) entered into a Purchase and Sponsor Handover Agreement (the “Purchase Agreement”) pursuant to which New Sponsor has agreed to purchase from the Old Sponsor, an aggregate of (i) 4,475,000 Class B Shares and (ii) 1,000,000 private placement warrants of the Company (the “Transferred Interests”), for an aggregate purchase price of $2,000,000 paid in cash at closing (the “Transaction”). The New Sponsor and Old Sponsor are collectively referred to herein as “Sponsor Parties”.

In connection with the Transaction, pursuant to the Purchase Agreement, Carter Glatt (Chief Executive Officer) and Michael Castaldy (Chief Financial Officer) resigned from their respective positions as officers of the Company, and the existing members of the board of directors, Carter Glatt, Michael Castaldy, Ben Coates, Jeron Smith and Cecil White agreed to resign as directors of the Company effective as of the 10 th day following the mailing by the Company of this proxy statement/information statement to the shareholders of the Company advising them of the Transaction and the other transactions contemplated by the Purchase Agreement, including the change in control of a majority of the board of directors, pursuant to Section 14(f) of the Exchange Act, and Rule 14(f) thereunder (the “Schedule 14F Change in Control Date”). Elliot Richmond was appointed as Chief Executive Officer and Chief Financial Officer of the Company effective as of the closing of the Transaction, and will serve as Chairman of the Board (as defined below) effective as of the Schedule 14F Change in Control Date, and David Bailin and Jeremy Sziklay will serve as independent directors effective as of the Schedule 14F Change in Control Date (the “New Management”). Accordingly, the purpose of the Name Change Proposal (as defined below) is to better reflect Company’s New Management. Please read this proxy statement/information statement carefully. It contains certain biographical and other information concerning the New Management to be in place following the Schedule 14F Change in Control Date.