TRIAN FUND MANAGEMENT, L.P. → JANUS HENDERSON GROUP PLC

Item 4 of the Schedule 13D is hereby amended and supplemented by adding the following: On June 16, 2026, the Issuer, Parent and Merger Sub entered into a side letter agreement (the "Side Letter"), which further supplements and amends limited terms of the Amended Merger Agreement (as further amended and supplemented by the Side Letter, the "Merger Agreement"). Among other things, the Side Letter provides that (i) the closing of the Merger will occur on June 30, 2026, subject to the satisfaction or waiver of all conditions to closing as set forth in the Merger Agreement (ii) conditions related to those regulatory approvals received in connection with the Merger as of the date of the Side Letter are satisfied as of the date of the Side Letter; and (iii) the date after which the Merger Agreement may be terminated if the Merger has not occurred on or prior to such date (referred to in the Merger Agreement as the Termination Date), shall be September 20, 2026. Importantly, while the Side Letter reflects an intention of the parties to effectuate closing of the Merger on June 30, 2026, it is noted that the closing remains subject to the satisfaction of all closing conditions in the Merger Agreement.