Form 8-K

8-K — JANUS HENDERSON GROUP PLC

Accession: 0001104659-26-075457

Filed: 2026-06-18

Period: 2026-06-16

CIK: 0001274173

SIC: 6282 (INVESTMENT ADVICE)

Item: Entry into a Material Definitive Agreement

Item: Regulation FD Disclosure

Item: Financial Statements and Exhibits

Documents

8-K — tm2618260d1_8k.htm (Primary)

EX-2.1(1) — EXHIBIT 2.1.1 (tm2618260d1_ex2d1-1.htm)

EX-99.1 — EXHIBIT 99.1 (tm2618260d1_ex99-1.htm)

GRAPHIC (tm2618260d1_8kimg01.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K — FORM 8-K

8-K (Primary)

Filename: tm2618260d1_8k.htm · Sequence: 1

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0001274173

2026-06-16

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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):

June 16, 2026

Commission File Number

001-38103

JANUS HENDERSON GROUP PLC

(Exact name of registrant

as specified in its charter)

Jersey, Channel Islands

98-1376360

(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)

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

by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405

of this chapter) or Rule 12b 2 of the Securities Exchange Act of 1934 (§240.12b 2 of this chapter).

Emerging growth company ¨

an emerging 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(a) of the Exchange

Act. o

Explanatory

Note

As previously announced, on December 21, 2025,

Janus Henderson Group plc (the “Company”) entered into the Agreement and Plan of Merger (the “Original Merger Agreement”

and, as amended by the Amendment (as defined below), the “Merger Agreement”), 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”), 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. On

March 24, 2026, the Company, Parent and Merger Sub entered into Amendment No. 1 to the Agreement and Plan of Merger (the “Amendment”),

pursuant to which certain terms of the Original Merger Agreement were amended. Subsequently, at the extraordinary general meeting of

shareholders of the Company held on April 16, 2026, the shareholders of the Company approved the proposal to approve and adopt the Merger

Agreement, as amended or supplemented from time to time, and the transactions contemplated by the Merger Agreement.

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:

i. 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.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit

Number

Description

2.1.1

Side Letter, dated as of June 16, 2026, by and among Janus Henderson Group plc, Jupiter Company Limited, and Jupiter Merger Sub Limited.

2.1.2*+

Agreement and Plan of Merger, dated as of December 21, 2025, by and among Janus Henderson Group plc, Jupiter Company Limited, and Jupiter Merger Sub Limited (incorporated by reference to Exhibit 2.1 of the Company’s Current Report on Form 8-K filed with the SEC on December 22, 2025).

2.1.3

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 (incorporated by reference to Exhibit 2.1 of the Company’s Current Report on Form 8-K filed with the SEC on March 24, 2026).

99.1

Press Release, dated as of June 18, 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.

Portions of this exhibit have been omitted pursuant to Item 601(b)(2)(ii) of Regulation S-K.

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 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.

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: June 18, 2026

JANUS

HENDERSON GROUP PLC

By:

/s/ Sukh Grewal

Name:

Sukh Grewal

Title:

Chief Financial Officer

EX-2.1(1) — EXHIBIT 2.1.1

EX-2.1(1)

Filename: tm2618260d1_ex2d1-1.htm · Sequence: 2

Exhibit 2.1.1

STRICTLY CONFIDENTIAL

VIA EMAIL

CONFIDENTIAL

June 16, 2026

Jupiter Company Limited

c/o Trian Fund Management, L.P.

280 Park Avenue, 41st Floor

New York, NY 10017

Attention:

Brian L. Schorr

Daniel R. Marx

Email:

bschorr@trianpartners.com

dmarx@trianpartners.com

General Catalyst Group Management, LLC

20 University Road, Fourth Floor

Cambridge, MA 02138

Attention:

Christopher McCain

E-mail:

cmccain@generalcatalyst.com

Re: Closing Date

Reference is made to the Agreement

and Plan of Merger, dated as of December 21, 2025 (as amended, modified or supplemented from time to time in accordance with its

terms, including by that certain Amendment No. 1, dated as of March 24, 2026, the “Merger Agreement”), by and among

Jupiter Company Limited, a company incorporated in Jersey (“Parent”), Jupiter Merger Sub Limited, a company incorporated

in Jersey and a wholly owned subsidiary of Parent (“Merger Sub”), and Janus Henderson Group plc, a company incorporated

in Jersey (the “Company” and together with Parent and Merger Sub, the “Parties”). Capitalized terms

used herein and not defined have the meaning given to them in the Merger Agreement.

The Parties acknowledge and agree as follows:

1. Pursuant to Section 1.2 of the Merger Agreement, the Parties hereby agree that the Closing shall

occur on June 30, 2026 subject to the satisfaction or waiver of all conditions set forth in Article VIII at or prior to the Closing

or, if any conditions set forth in Article VIII have not been satisfied or waived as of June 30, 2026, then the Closing shall occur

(a) seven (7) Business Days after the date upon which all conditions set forth in Article VIII 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, to the extent permitted

by law, waiver thereof at the Closing) or (b) such other date as Parent and the Company shall mutually agree in writing.

2. As of the date hereof, the Parties hereby acknowledge and agree that the conditions to the obligations

of the Company, Parent and Merger Sub to effect the Merger set forth in Section 8.1 of the Merger Agreement (other than the conditions

set forth in Section 8.1(b), which would be satisfied as of the date of this letter agreement if the Closing Date were to be the

date of this letter agreement) have been satisfied.

3. Section 9.1(b) of the Merger Agreement is hereby amended and restated in its entirety to read as follows:

“By either

the Company or Parent if the Effective Time shall not have occurred on or before September 20, 2026 (the “Termination Date”);

provided, however, that the right to terminate this Agreement under this Section 9.1(b) shall not be available to

any party whose failure to fulfill any obligation under this Agreement has been the primary cause of the failure of the Effective Time

to occur on or before the Termination Date and such action or failure to perform constitutes a breach of this Agreement;”.

4. Section 8.1(d) of the Company Disclosure Schedule is hereby amended to delete Item 8 therefrom in its entirety.

5. Section 7.15 of the Merger Agreement is hereby amended and restated in its entirety to read as follows:

“Immediately

prior to the Effective Time, Jupiter Borrower, Inc., a Delaware corporation and Wholly Owned Subsidiary of Merger Sub (“Debt

Merger Sub”), shall incur the Debt Financing. Debt Merger Sub shall distribute the proceeds of the Debt Financing to Merger

Sub, which will in turn lend such proceeds to Parent. Substantially contemporaneously with the Effective Time, Debt Merger Sub shall merge

with and into Janus Henderson US (Holdings) Inc., a Wholly Owned Subsidiary of the Company (“Janus Henderson US”, and

such merger, the “Debt Merger”), with Janus Henderson US continuing as the surviving corporation. The Parties intend

that for U.S. federal income tax purposes the Debt Financing be treated as incurred by Janus Henderson US and the distribution of the

proceeds of the Debt Financing be treated as made by Janus Henderson US to the Company.”

Except as otherwise

expressly provided herein, the Merger Agreement shall remain unchanged and in full force and effect, and, to the extent applicable, such

terms shall apply to this letter agreement as if it formed a part of the Merger Agreement. From and after the execution of this letter

agreement by the parties hereto, any reference to the Merger Agreement, and each reference in the Merger Agreement to “this Agreement,”

“hereof,” “herein,” “hereby,” “hereto,” “herewith,” “hereunder”

and derivative or similar words, shall be deemed to be a reference to the Merger Agreement as supplemented by this letter agreement. Each

reference in the Merger Agreement, as supplemented hereby, to “the Effective Date”, “the date of this Agreement”,

“the date hereof” or any similar reference shall continue to refer to December 21, 2025.

Sections 10.3 (Successors

and Assigns), 10.4 (Governing Law; Jurisdiction; Specific Performance), 10.5 (Expenses), 10.6 (Severability; Construction), 10.7 (Notices),

10.8 (Entire Agreement), 10.9 (Parties in Interest), 10.10 (Section and Paragraph Headings), 10.11 (Counterparts), Section 10.14

(Non-Recourse) and 10.15 (Interpretative Provisions) of the Merger Agreement shall apply mutatis mutandis to this letter agreement.

[Signature Page Follows.]

-2-

Please indicate your understanding and agreement

with the foregoing by signing a copy of this letter agreement where indicated below and returning it to our attention.

Sincerely,

JANUS HENDERSON GROUP PLC

/s/ Ali Dibadj

Name:

Ali Dibadj

Title:

Chief Executive Officer

[Signature Page to Closing Date Letter Agreement]

Acknowledged and agreed,

JUPITER

COMPANY LIMITED

/s/ Peter W. May

Name:

Peter W. May

Title:

Authorized Signatory

JUPITER

MERGER SUB LIMITED

/s/ Peter W. May

Name:

Peter W. May

Title:

Authorized Signatory

[Signature Page to Closing Date Letter Agreement]

EX-99.1 — EXHIBIT 99.1

EX-99.1

Filename: tm2618260d1_ex99-1.htm · Sequence: 3

Exhibit 99.1

Janus

Henderson Announces Receipt of Required Regulatory Approvals and

Client Consents following Resounding Shareholder Approval of the Trian and General

Catalyst Take-Private Transaction

Anticipates June 30, 2026 Closing Date

June 18, 2026

LONDON -- Janus Henderson Group plc (NYSE: JHG; “Janus

Henderson”, or the “Company”) today announced that it has secured the regulatory approvals and client consents required

to complete its previously announced take-private transaction with Trian Fund Management, L.P. and its affiliated funds (“Trian”),

and General Catalyst Group Management, LLC and its affiliated funds (“General Catalyst”). The receipt of required regulatory

approvals and client consents represents a significant milestone toward the completion of the transaction with Trian and General Catalyst

following the earlier announced resounding shareholder approval.

The take-private transaction with Trian and General Catalyst is expected

to close on June 30, 2026, subject to the continued satisfaction of all closing conditions under the definitive agreement for the transaction.

At the closing, pursuant to the definitive agreement for the transaction

dated December 21, 2025, as amended, holders of Janus Henderson shares not already owned or controlled by Trian will be converted into

a right to receive $52.00 per share in cash. Upon completion of the transaction, Janus Henderson will become a privately held company,

and its ordinary shares will be delisted from the NYSE.

Trian and General Catalyst have great respect for the Janus Henderson

team and are excited to partner with them to invest in growth, as a private company for the benefit of its clients.

Forward Looking Statements

Certain statements in this press release 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 press release include,

but are not limited to, 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