Fund manager Gartmore has announced that it will be putting the company up for sale or restructuring following the exit of its European Large Cap team head Roger Guy on Sunday night.

Gartmore's stock value plummeted 15 per cent to 107p after the company's fund manager announced his decision to take a break from day-to-day fund management and quit altogether in May 2011.

An important figure in the company and the hedge fund sector, his departure is expected to cause many investor withdrawals.

Already, Skandia Investment Group announced that it would be pulling out of its €38m mandate with the company overseen by Guy.

Killik & Co has also withdrawn funds from Gartmore.

"We are hopeful that we can keep as many of the assets as possible but I would not be surprised to see a lot of departures," said chief executive Jeff Mayer commenting it was too soon to tell how many investors would depart.

The company has engaged Goldman Sachs to undertake a complete strategic review of Gartmore's options which include a sale, strategic partnership or a management buyout.

US investor Henderson, Schroders, Aberdeen Asset Management and Man Group are among the potential buyers.