Interactive Brokers Group, Inc. - Form 8-K Filing

On July 31, 2026, Interactive Brokers Group, Inc. filed a Form 8-K to report the filing of a Prospectus Supplement under Rule 424(b)(5). This supplement registers up to 920,000 shares of the Company's common stock, available under its shelf Registration Statement on Form S-3 (Registration Statement No. 333-297857) filed on the same date. The filing also includes a legal opinion letter from Dechert LLP regarding the validity of these shares, which is incorporated by reference into the Registration Statement as Exhibit 5.3. The shares are intended for promotions aimed at attracting new customers. The Chief Financial Officer, Treasurer, and Secretary, Paul J. Brody, signed the report.