Assistant manager Alasdair McKinnon will become acting manager of the £821m company effective from 18 July. He has been with the company since 2003.
For short period after stepping down, John Kennedy will stay on as a consultant to supervise the handover of responsibility.
The cumulative performance of the fund measured -0.3% in the past year, compared to the IMA Global index that delivered 5.3%, according to FE Analytics.
