UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2019 OR for the transition period from to 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) 201 Bishopsgate London, United Kingdom (Address of princi ...