The CEO of AssetCo, Campbell Fleming, is exiting the firm at the end of this month, according to the group.
In a statement, AssetCo's board said Fleming was "leaving for personal reasons", with 30 June set as his final day as CEO.
The board said it would not be replacing Fleming immediately as this was "consistent with the holding company nature".
Head of distribution Gary Collins departs AssetCo
Instead, chair Martin Gilbert and chief financial and operating officer Gary Marshall will split the CEO responsibilities, with Gilbert taking the lead on the overall strategic direction of the firm and Marshall overseeing the day-to-day operations of the business.
Alex Hoctor-Duncan, CEO of AssetCo's principal operating company River and Mercantile, has already taken on additional responsibilities, while the firm's equities businesses integrate under the former's brand.
Fleming commented it had been "an extremely demanding 20 months integrating the group" and said it was the "right business and personal decision to step down".
He said: "I will continue to support, as well as remain a shareholder of, AssetCo as I believe in its strategy, team and its people who continue to deliver for our clients as shown by our results."
Gilbert extended his thanks to Fleming and said the board was "grateful to Campbell for his efforts" and hoped to continue its "long association with him in supporting and guiding some of AssetCo's underlying businesses".
