The legendary money manager is losing his No. 2, Kumar Palghat, who will become co-manager of a new Janus Short Duration Income ETF.
Dividend Growth attracted $3 billion over the past six months and its assets have almost doubled over the past three years.
In its asset management business, State Street had net outflows of $35 billion in the quarter.
The turn to an outsider marks the latest twist in a struggle to regain footing after a steep decline.
Johnson has overseen the $849 million Pimco EqS Long/Short Fund, which takes positions in stocks he selected, since its 2003 inception at his previous firm.