Schedule 13D Filing by Massachusetts Mutual Life Insurance Co.

Massachusetts Mutual Life Insurance Company (MassMutual) has filed a Schedule 13D detailing its beneficial ownership of Janus Henderson Group plc (the Issuer). MassMutual reports owning 9,283.527 Ordinary Shares, representing 0.1% of the outstanding shares. This ownership is primarily held in advisory accounts. The filing is in connection with a merger agreement entered into on December 21, 2025, between the Issuer, Jupiter Company Limited (Parent), and Jupiter Merger Sub Limited (Merger Sub). Pursuant to the agreement, Merger Sub will merge with the Issuer, with the Issuer continuing as a subsidiary of Parent. Each Ordinary Share will be converted into $49.00 in cash. MassMutual has committed to purchasing up to $1,000,000,000 in preferred equity of Parent at the closing of the merger, subject to certain conditions. The filing also notes that MassMutual and Trian Fund Management, L.P. may be deemed to be acting as a group for purposes of Rule 13d-5 under the Exchange Act, although MassMutual expressly disclaims beneficial ownership of securities held by Trian.