Sam Isaly has resigned as joint manager of the £1.2bn Worldwide Healthcare Investment trust, amid accusations of misconduct.
Mr Isaly was employed by Orbimed, a US healthcare investment house that had the contract to run the Worldwide Healthcare trust.
He had worked as joint manager of the trust for 22 years.
In recent days, US media outlet Bloomberg has reported accusations of inappropriate sexual behaviour against Mr Isalay from employees in the US.
In an announcement to the stock exchange this morning, the trust confirmed Mr Isaly has resigned from all of his responsibilities at the company.
The trust will continue to be managed by Sven Borho, who is the other joint manager of the trust and has been part of the management of the trust for 22 years.
The trust currently has 70 per cent of its capital invested in large cap companies, and 30 per cent in small caps. None of the top ten holdings are UK-listed businesses.
The Worldwide Healthcare trust has returned 44 per cent over the past three years, compared with 35 per cent for the average trust in the AIC Biotechnology and Healthcare sector in the same time period.