Form DEFA14A JANUS INVESTMENT FUND

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

Janus Investment Fund

(Name of Registrant as Specified in Its Charters)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

[Advisor Firm’s Logo]

Dear [First Name/Last Name]:

[Advisor Name] at [Advisor’s Firm Name] encourages you to participate in the Joint Special Meeting of Shareholders for your Janus Henderson mutual fund.

Your vote is needed to approve a new investment advisory agreement to allow Janus Henderson to continue managing your mutual fund following the proposed acquisition of Janus Henderson by Trian and General Catalyst.

The terms of your mutual fund’s new advisory agreement are substantially identical to those of your mutual fund’s current advisory agreements. There is no change in the fee rate payable by your mutual fund to the adviser.

The Board of Trustees of your mutual fund unanimously recommends that shareholders vote “FOR” all proposals.

Your vote is very important, please vote today!

Simply use one of the following methods to promptly provide your voting instructions:

CLICK HERE TO VOTE (link will be specific to each holder)

Please vote today. We urge you to submit your vote before May 18^th, 2026.

Detailed information on the meeting and the proposals can be found by visiting Janus Investment Fund, SEC Filings.

[Advisor logo]

Dear [First Name/Last Name]:

[Advisor Name] at [Advisor’s Firm Name] encourages you to participate in the Joint Special Meeting of Shareholders for your Janus Henderson mutual fund.

Your vote is needed to approve a new investment advisory agreement to allow Janus Henderson to continue managing your mutual fund following the proposed acquisition of Janus Henderson by Trian and General Catalyst.

The terms of your mutual fund’s new advisory agreement are substantially identical to those of your mutual fund’s current advisory agreements. There is no change in the fee rate payable by your mutual fund to the adviser.

The Board of Trustees of your mutual fund unanimously recommends that shareholders vote “FOR” all proposals.

Your vote is very important, please vote today!

Simply use one of the following methods to promptly provide your voting instructions:

Please vote today. We urge you to submit your vote before May 18^th, 2026.

Detailed information on the meeting and the proposals can be found by visiting Janus Investment Fund, SEC Filings.

Dear [Advisor Name],

We encourage you to watch the below video from Michael Schweitzer, regarding an important upcoming shareholder vote for Janus Henderson funds.

[VIDEO THUMBNAIL]

Your partnership is critical in helping ensure a smooth process. We ask that you encourage clients to vote their shares and return their proxy promptly to help avoid additional follow-up communications from our proxy solicitor.

Thank you for your continued trust and confidence in Janus Henderson.