Form DEFA14A Janus Detroit Street

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 Detroit Street Trust

(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):

Alliance Shareholder Communications 200 Broadacres Drive, 3rd Fl. Bloomfield, NJ 07003 Important Proxy Voting Reminder Vote Today Mutual Fund shareholders: To VOTE call 1-855-206-2338 ETF shareholders: To VOTE call 1-855-206-2309 Proxy voting specialists are available 9:00 a.m.–10:00 p.m. Eastern Time Monday through Friday, and 10:00 a.m.–8:00 p.m. Saturday and Sunday. 2 Minutes. One Vote. Same Janus Henderson. More than 46% of your fellow shareholders have voted on the proposal, but we need 50%. Please join your peers by voting now. 260529-allianceJanus8.5x11.indd 1 6/19/26 2:55 PM

Same team. Same strategy. Same fee. Your vote keeps it that way. Your Vote Is Needed Please cast your proxy vote before the June 29, 2026 Joint Special Meeting of Shareholders. The Board unanimously recommends that shareholders vote FOR the proposal to approve a new investment advisory agreement. Your Vote Is Important Vote Today Mutual Fund shareholders: To VOTE call 1-855-206-2338 ETF shareholders: To VOTE call 1-855-206-2309 Proxy voting specialists are available 9:00 a.m.–10:00 p.m. Eastern Time Monday through Friday, and 10:00 a.m.–8:00 p.m. Saturday and Sunday. 260529-allianceJanus8.5x11.indd 2 6/19/26 2:55 PM