The managers currently run several firms at the company including the DWS Top Dividende fund.
Gebhardt announced plans to depart the company in September 2016. He will join Berenberg Bank as chief investment officer at the start of next year.
In his new post, Gebhardt replaces the firm's current CIO, Manfred Schlumberger, who has held the position for a year.
At Deutsche AM, Schüssler will also take on the position as interim head of US equities, after the departure of Joe Benevento.