Material Event (Form 8-K)

On January 13, 2026, CG Oncology, Inc. (the "Company") filed Amendment No. 1 to Prospectus (the "Amendment") with the Securities and Exchange Commission (the "SEC") for the offer and sale of shares of its common stock, par value $0.0001 per share, having an aggregate offering price of up to $550,000,000 (the "Shares"), pursuant to that certain Open Market Sale Agreement, dated March 28, 2025, by and between the Company and Jefferies LLC (the "Sales Agreement"). The Amendment amends and supplements the information in the prospectus dated March 28, 2025 (the "Prospectus") filed with the SEC as part of the Company's Registration Statement on Form S-3ASR(File No. 333-286230),relating to the offer and sale of up to $250,000,000 of shares of the Company's common stock pursuant to the Sales Agreement. The Amendment should be read in conjunction with the Prospectus, and is qualified by reference thereto, except to the extent that the information therein amends or supersedes the information contained in the Prospectus. The Amendment is not complete without, and may only be delivered or utilized in connection with, the Prospectus and any future amendments or supplements thereto.

The Company previously sold an aggregate of 5,861,984 Shares for gross proceeds of $250,000,000 under the Sales Agreement. The Company filed the Amendment to increase the Shares available to be sold pursuant to the terms of the Sales Agreement by an additional $300,000,000, for an aggregate offering price of up to $550,000,000.

A copy of the opinion of Cooley LLP relating to the validity of the Shares is attached as Exhibit 5.1 hereto.