Effective 1 April, Goldstone will take on the £286m Keystone Investment Trust, managed by Barnett for the past 14 years.
In October, Goldstone also took on Barnett’s UK equity mandate of Invesco Perpetual Select Trust, while having also recently assumed responsibility for the UK portion of a pan-European equity mandate.
In a stockmarket announcement, Beatrice Hollond, chairman of Keystone said: “Fourteen years ago the board took the decision to appoint a talented young fund manager called Mark Barnett.
“Mark has produced outstanding returns for shareholders and the board would like to take this opportunity to thank Mark for his many achievements and for producing superior long-term returns for shareholders.
“Over the last few years Mark’s responsibilities have grown significantly and the board believes that the time is now right for him to pass the baton to one of the rising stars of his team.
“The board has been highly impressed by James Goldstone and is confident that he is the right investor to take over management of Keystone from Mark”.
The Keystone board has also lowered the company’s management fee, down from 0.6% to 0.45%, also effective from 1 April.