Gilchrist resigned from Marsico Capital Management, sub-adviser of the fund’s strategy, last Friday and the fund has subsequently lost its A rating.
He left to pursue personal opportunities and to take some time out of fund management.
Henderson US Opportunities will now be managed by Brandon Geisler, who has been an analyst in the Marsico team since 2006.
Geisler has nine years of experience in the financial services and prior to Marsico he was at Goldman Sachs where he was vice president in equity research covering consumer related groups.
The fund has $15.58m of assets and lost 17.6% in the year to 31 August, compared to losses of 5.6% from the benchmark.
Over one year and five years and since inception, the fund has underperformed its benchmark.
Richard Acworth, spokesperson for Henderson Global Investors, said: "It’s understandable OBSR would want to take time to assess the new fund manager’s ability, that is prudent to do. It’s in much the same way that consultants will often take funds off their watch list if there’s a change of manager because it is an unknown context.
"But Geisler is very competent and we have every faith in him."
He said the fundamental investment orientation of the fund would not change with the new manager, but it was likely Geisler would make some changes at a stock and sector level.
OBSR said it will continue to monitor the fund’s progress under the new manager.
