Material Agreement, Financial Obligation, Private Placement (Form 8-K)

Amended and Restated Working Capital Note

On February 11, 2026, Yorkville Acquisition Corp. (the "Company") issued a convertible unsecured promissory note (the "Prior Note") in the aggregate principal amount of $250,000.00 to Yorkville Acquisition Sponsor, LLC, a Delaware limited liability company (the "Sponsor"), in order to provide the Company with additional working capital, as previously disclosed in the Company's Current Report on Form 8-K filed with the U.S. Securities and Exchange Commission (the "SEC") on February 17, 2026. On May 4, 2026, the Sponsor advanced an additional $250,000 to the Company for additional working capital purposes. Also on May 4, 2026, in order to document such additional advance, the Company issued an amended and restated convertible unsecured promissory note (the "Amended and Restated Working Capital Note") in the aggregate principal amount of $500,000.00 to the Sponsor, which amends, restates, supersedes and replaces the Prior Note in its entirety. Pursuant to the terms of the Amended and Restated Working Capital Note, the principal balance shall not accrue interest; shall be payable by the Company on the earlier of the date on which the Company consummates its initial business combination or the date that the winding up of the Company is effective; and is convertible at the Sponsor's election upon the consummation of the Company's initial business combination. Should the Sponsor elect to convert all or a portion of the principal balance, the elected principal balance amount will convert, at a price of $10.00 per unit, into units identical to the private placement units issued in connection with the Company's initial public offering (each, a "New Unit"), rounded down to the nearest whole number.

The foregoing description of the Amended and Restated Working Capital Note does not purport to be complete and is qualified in its entirety by reference to the full text of the Amended and Restated Working Capital Note, which is filed hereto as Exhibit 10.1 and which is incorporated herein by reference.

The information disclosed under Item 1.01 of this Current Report on Form 8-K is incorporated by reference into this Item 2.03.

The information disclosed under Item 1.01 of this Current Report on Form 8-K is incorporated by reference into this Item 3.02. The Amended and Restated Working Capital Note shall be convertible into a maximum of 50,000 New Units. Each New Unit will consist of one Class A ordinary share of the Company, par value $0.0001 per share (each, a "Class A Ordinary Share"), and one-third of one redeemable warrant, with each whole warrant entitling the holder to purchase one Class A Ordinary Share, at an exercise price of $11.50 per share, which will become exercisable 30 days after the completion of the Company's initial business combination, subject to certain terms and conditions.

The Company has relied upon Section 4(a)(2) of the Securities Act of 1933, as amended, in connection with the issuance of the Amended and Restated Working Capital Note.