UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):~~January~~ March 3024, 2026

Commission File Number 001-38103

JANUS HENDERSON GROUP PLC

(Exact name of registrant as specified in its charter)

Jersey, Channel Islands (State or other jurisdiction of incorporation or organization)	98-1376360 (I.R.S. Employer Identification No.)
Jersey, Channel Islands	98-1376360
201 Bishopsgate London, United Kingdom (Address of principal executive offices)	EC2M3AE (Zip Code)
(State or other jurisdiction of	(I.R.S. Employer
incorporation or organization)	Identification No.)

201 Bishopsgate	EC2M3AE
London, United Kingdom	(Zip Code)
(Address of principal executive offices)

+44 (0) 20 7818 1818

(Registrant’s telephone number, including area code)

N/A ~~(Former name, former address and former fiscal year, if changed since last report)~~

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $1.50 Per Share Par Value	JHG	New York Stock Exchange

Check the appropriate box below if the Form 8‑-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a‑12 under the Exchange Act (17 CFR 240.14a‑12) ☐ Pre-commencement communications pursuant to Rule 14d‑2(b) under the Exchange Act (17 CFR 240.14d‑2(b)) ☐ Pre-commencement communications pursuant to Rule 13e‑4(c) under the Exchange Act (17 CFR 240.13e‑4(c))

~~Indicate~~¨ bySoliciting ~~check~~material ~~mark~~pursuant ~~whether~~to ~~the registrant is an emerging growth company as defined in~~ Rule ~~405~~ of14a-12 ~~the~~under ~~Securities Act of 1933 (§230.405 of this chapter) or Rule 12b‑2 of~~ the ~~Securities~~ Exchange Act of(17 ~~1934~~CFR (§240.~~12b‑2 of this chapter~~14a-12).

~~Emerging~~¨ ~~growth~~Pre-commencement ~~company ☐~~communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

If¨ anPre-commencement ~~emerging~~communications ~~growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided~~ pursuant to ~~Section 13~~Rule 13e-4(ac) of under the Exchange Act (17 CFR 240. ☐13e-4(c))

~~Item~~Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 2405 of the Securities Act of 1933 (§230.~~02 Results~~405 of this chapter) or Rule 12b-2 of ~~Operations~~the ~~and~~Securities ~~Financial~~Exchange ~~Condition~~Act of 1934 (§240.12b-2 of this chapter).

OnEmerging ~~January~~growth ~~30,~~company 2026, Janus Henderson Group plc issued a press release reporting its financial results for the fourth quarter and full-year 2025. A copy of that press release is being furnished as Exhibit 99.1 to this Current Report.¨

~~Item 9.01 Financial~~If an ~~Statements~~emerging ~~and~~growth ~~Exhibits~~company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

~~(d) Exhibits~~Item 1.01 ~~The~~Entry ~~following~~into ~~exhibits~~a ~~are~~Material ~~being~~Definitive ~~furnished herewith~~Agreement.

Exhibit Number		Description
99.1		Janus Henderson Group plc press release reporting its financial results for the fourth quarter and full-year 2025.
104		Cover Page Interactive Data File - The cover page interactive data file does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

Amendment to Agreement and Plan of Merger

~~SIGNATURE~~On March 24, 2026, Janus Henderson Group plc (the “Company”), entered into Amendment No. 1 to the Agreement and Plan of Merger (the “Amendment”) with Jupiter Company Limited, a company incorporated in Jersey (“Parent”), and Jupiter Merger Sub Limited, a company incorporated in Jersey and a wholly owned subsidiary of Parent (“Merger Sub”), which amends the previously announced Agreement and Plan of Merger, dated as of December 21, 2025 (the “Original Merger Agreement” and, the Original Merger Agreement as amended, supplemented and otherwise modified by the Amendment, the “Amended Merger Agreement”), pursuant to which Merger Sub will merge with and into the Company (the “Merger”) in accordance with the Companies (Jersey) Law 1991, with the Company continuing as the surviving company and a wholly owned subsidiary of Parent. Capitalized terms used but not defined herein shall have the meanings ascribed to such terms in the Amended Merger Agreement.

~~Pursuant~~Under to the ~~requirements~~terms of the ~~Securities~~Amendment, ~~Exchange~~the ~~Act of 1934~~Company, Parent ~~the~~and ~~registrant~~Merger ~~has~~Sub ~~duly~~have ~~caused~~agreed, ~~this~~as ~~report~~compared to bethe ~~signed~~Original onMerger ~~its~~Agreement ~~behalf~~and byamong ~~the~~other ~~undersigned~~things, ~~hereunto duly authorized.~~to:

	Janus Henderson Group plc
Date: January 30, 2026	By:	/s/ Roger Thompson
		Roger Thompson
		Chief Financial Officer

increase the cash consideration to be paid by Parent for each ordinary share, par value $1.50 per share, of the Company (collectively, the “Shares”) issued and outstanding immediately prior to the Effective Time (except for shares held by Parent and as otherwise provided in the Amended Merger Agreement) from $49.00 to $52.00 per Share in cash, without interest;

3 ii. modify the amount payable by the Company if either Parent or the Company terminates the Amended Merger Agreement because of the failure to obtain the Required Company Vote from a reimbursement of certain fees and expenses actually incurred by or on Parent’s behalf, not to exceed $111,420,000, to a fixed payment of $118,200,000 (the “Expense Reimbursement Payment”);

iii.

increase the fees payable by the Company upon termination of the Amended Merger Agreement under specified circumstances (including if the Company terminates the Amended Merger Agreement in order to enter into an alternative transaction that constitutes a Superior Proposal), from (a) $297,130,000 to $394,000,000 if the Expense Reimbursement Payment has not been paid or (b) $222,850,000 to $275,800,000 if the Expense Reimbursement Payment has been paid;

iv.

allow the Company to declare, set aside or pay a quarterly dividend not to exceed $1.00 per share of Company Common Stock beginning with fiscal quarters commencing on or after July 1, 2026, with declaration and payment dates consistent with past practice, and subject to the prior satisfaction or waiver by Parent of certain conditions, including (but not limited to) receipt of the (a) Required Company Vote to approve the Merger and (b) required Client Consent Percentage; and

allow Parent to, following receipt of the Required Company Vote and subject to compliance with Applicable Law, make available to employees of the Company capacity for rollover and other equity purchase and/or participation opportunities, such employees to be identified based on their expressed interest and in consultation with senior management of the Company, provided that no such opportunity shall create any obligation or other liability of the Company prior to the Closing.

The foregoing description of the Amendment and the Amended Merger Agreement does not purport to be a complete statement and is qualified in its entirety by reference to the Amendment, which is attached as Exhibit 2.1 to this Current Report on Form 8-K and incorporated herein by reference, and 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 and incorporated herein by reference.

Item 8.01 Other Events.

On March 24, 2026, the Company issued a press release announcing the signing of the Amendment. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Forward Looking Statements

Certain statements in this Form 8-K not based on historical facts are “forward-looking statements” within the meaning of the federal securities laws. Such forward-looking statements involve known and unknown risks and uncertainties that are difficult to predict and could cause our actual results, performance or achievements to differ materially from those discussed. These include statements as to our future expectations, beliefs, plans, strategies, objectives, events, conditions, financial performance, prospects or future events, including with respect to the timing and anticipated benefits of pending and recently completed transactions and strategic partnerships, and expectations regarding opportunities that align with our strategy. In some cases, forward-looking statements can be identified by the use of words such as “may,” “could,” “expect,” “intend,” “plan,” “seek,” “anticipate,” “believe,” “estimate,” “predict,” “potential,” “continue,” “likely,” “will,” “would,” and similar words and phrases. Forward-looking statements are necessarily based on estimates and assumptions that, while considered reasonable by us and our management, are inherently uncertain. Accordingly, you should not place undue reliance on forward-looking statements, which speak only as of the date they are made and are not guarantees of future performance. We do not undertake any obligation to publicly update or revise these forward-looking statements.

Various risks, uncertainties, assumptions and factors that could cause our future results to differ materially from those expressed by the forward-looking statements included in this Form 8-K include, but are not limited to, the impact of any alternative proposal, Janus Henderson’s ability to obtain the regulatory, shareholder and other approvals required to consummate the proposed transaction and the timing of the closing of the proposed transaction, including the risks that a condition to closing would not be satisfied within the expected timeframe or at all or that the closing of the proposed transaction would not occur, the outcome of any legal proceedings that may be instituted against the parties and others related to the merger agreement, that shareholder litigation in connection with the proposed transaction may affect the timing or occurrence of the proposed transaction or result in significant costs of defense, indemnification and liability, unanticipated difficulties or expenditures relating to the proposed transaction, including the impact of the transaction on Janus Henderson’s business, that the proposed transaction generally may involve unexpected costs, liabilities or delays, that the business of Janus Henderson may suffer as a result of uncertainty surrounding the proposed transaction or the identity of the purchaser, that Janus Henderson may be adversely affected by other economic, business, and/or competitive factors, including the net asset value of assets in certain of Janus Henderson’s funds, and/or potential difficulties in employee retention as a result of the announcement and pendency of the proposed transaction, changes in interest rates and inflation, changes in trade policies (including the imposition of new or increased tariffs), volatility or disruption in financial markets, our investment performance as compared to third-party benchmarks or competitive products, redemptions, and other risks, uncertainties, assumptions, and factors discussed in our Annual Report on Form 10-K for the year ended December 31, 2025, and in other filings or furnishings made by Janus Henderson with the SEC from time to time.

Important Additional Information and Where to Find It

In connection with the proposed transaction, Janus Henderson Group plc (“Janus Henderson”) filed a definitive proxy statement with the U.S. Securities and Exchange Commission (the “SEC”) on March 11, 2026, which was first mailed to Janus Henderson’s shareholders on or about March 12, 2026. Janus Henderson and affiliates of Janus Henderson jointly filed a transaction statement on Schedule 13E-3 on March 11, 2026. Janus Henderson may also file other documents with the SEC regarding the proposed transaction, including amendments or supplements to the proxy statement or Schedule 13E-3. This communication is not a substitute for the proxy statement, the Schedule 13E-3 or any other document that may be filed by Janus Henderson with the SEC. INVESTORS AND SECURITY HOLDERS OF JANUS HENDERSON ARE URGED TO READ THE PROXY STATEMENT, THE SCHEDULE 13E-3 AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY, BECAUSE THEY CONTAIN OR WILL CONTAIN IMPORTANT INFORMATION. Investors and security holders may obtain the proxy statement and the Schedule 13E-3 and other documents that are filed with the SEC by Janus Henderson free of charge from the SEC’s website at https://www.sec.gov or through the investor relations section of Janus Henderson’s website at https://ir.janushenderson.com.

Participants in the Solicitation

Janus Henderson and its directors and certain of its executive officers and other employees may be deemed to be participants in the solicitation of proxies from Janus Henderson’s shareholders in connection with the proposed transaction. Information about the directors and executive officers of Janus Henderson and their ownership of Janus Henderson common shares is contained in the definitive proxy statement for Janus Henderson’s 2025 annual meeting of shareholders (the “Annual Meeting Proxy Statement”), which was filed with the SEC on March 21, 2025, including under the headings “Proposal 1: Election of Directors,” “Corporate Governance,” “Board Compensation,” “Proposal 2: Advisory Say-on-Pay Vote on Executive Compensation,” “Executive Compensation,” “Executive Compensation Tables,” “Securities Ownership of Certain Beneficial Owners and Management” and “Our Executive Officers.” Additional information regarding the persons who may, under the rules of the SEC, be deemed participants in the solicitation of the shareholders of Janus Henderson in connection with the proposed transaction, including a description of their direct or indirect interests, by security holdings or otherwise, has been included in the definitive proxy statement relating to the proposed transaction. To the extent holdings of securities by potential participants (or the identity of such participants) have changed since the information printed in the Annual Meeting Proxy Statement, such information has been or will be reflected on the Statements of Change in Ownership of Janus Henderson on Forms 3 and 4 filed with the SEC. Free copies of the proxy statement relating to the proposed transaction and free copies of the other SEC filings to which reference is made in this paragraph may be obtained from the SEC’s website at https://www.sec.gov or through the investor relations section of Janus Henderson’s website at https://ir.janushenderson.com.

Item 9.01 Financial Statements and Exhibits

(d) Exhibits

The exhibits listed on the Exhibit Index are incorporated herein by reference.

Exhibit Number		Description
2.1*		Amendment No. 1 to the Agreement and Plan of Merger, dated as of March 24, 2026, by and among Janus Henderson Group plc, Jupiter Company Limited, and Jupiter Merger Sub Limited.
99.1		Press Release, dated as of March 24, 2026.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

* Certain schedules and attachments have been omitted pursuant to Item 601(a)(5) of Regulation S-K.

Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: March 24, 2026

	JANUS HENDERSON GROUP PLC


	By:	/s/ Michelle Rosenberg
	Name:	Michelle Rosenberg
	Title:	General Counsel and Company Secretary

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