Andrew Holliman is to leave Threadneedle after seven years with the firm.
It is understood that Holliman is to join Polar Capital to launch a new fund, although the firm is yet to confirm this.
Cormac Weldon, Threadneedle’s head of US equities, will take over as lead manager of the £1.6bn American fund, assisted by fund manager Stephen Moore. Jeremy Podger will run the £9.5m Global Extended Alpha fund, helped by global equity fund manager Steve Thornber.
Under Holliman’s tenure, the American fund delivered a top-decile return of 36.2 per cent over five years to May 6, against the IMA North American sector’s 20.4 per cent, according to Morningstar.
Threadneedle chief investment officer Mark Burgess says: “While we are disappointed, we believe Threadneedle’s collaborative, team-based approach underlies our successful performance across asset classes, including in US equities. Our US equities performance has been particularly strong under the leadership of Cormac Weldon, who has been with Threadneedle for 14 years, and I am confident this will continue.”