Janus Henderson Group Ltd.

Item 1.01 Entry into a Material Definitive Agreement. Amendment to Agreement and Plan of Merger On June 16, 2026, the Company entered into a side letter agreement (the “Side Letter”) with Parent and Merger Sub, which further supplements and amends certain terms of the Merger Agreement (as further amended and supplemented by the Side Letter, the “Amended Merger Agreement”). Pursuant to the terms of the Side Letter, the Company, Parent and Merger Sub have agreed that, among other things: the closing of the Merger (the “Closing”) shall occur on June 30, 2026, subject to the satisfaction or waiver of all conditions to Closing as set forth in the Amended Merger Agreement, or if any Closing conditions set forth in the Amended Merger Agreement have not been satisfied or waived as of June 30, 2026, then Closing shall occur seven (7) Business Days after the date upon which all Closing conditions set forth in the Amended Merger Agreement have been satisfied or waived (other than those conditions which by their nature cannot be satisfied until the Closing, but subject to the satisfaction or waiver thereof) or on such other date as Parent and the Company mutually agree in writing; ii. conditions related to those regulatory approvals received 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. ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── The foregoing description of the Side Letter does not purport to be a complete statement and is qualified in its entirety by reference to (a) the Side Letter, which is attached as Exhibit 2.1.1 to this Current Report on Form 8-K and incorporated herein by reference, (b) the Original Merger Agreement, which is attached as Exhibit 2.1 to the previously filed Current Report on Form 8-K filed by the Company on December 22, 2025 with the Securities and Exchange Commission (the “SEC”) and incorporated herein by reference, and (c) the Amendment, which is attached as Exhibit 2.1 to the previously filed Current Report on Form 8-K filed by the Company on March 24, 2026 with the SEC and incorporated herein by reference.

Item 7.01 Regulation FD Disclosure. On June 18, 2026, the Company issued a press release announcing that it has secured the regulatory approvals and client consents required to complete its previously announced take-private transaction. The transaction is expected to close on June 30, 2026, subject to the continued satisfaction of all closing conditions under the Amended Merger Agreement. A copy of the press release is furnished as Exhibit 99.1 hereto. The information in this Item 7.01 and Exhibit 99.1 attached hereto is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as set forth by specific reference in such filing.