Man said on Monday Finance Director Kevin Hayes had left to pursue other professional interests with immediate effect, to be replaced by Jonathan Sorrell, son of WPP Plc (WPP.L) Chief Martin Sorrell and formerly Man's head of strategy and corporate finance.

The departure was revealed on the same day Man - Europe's largest listed hedge fund firm - dropped out of Britain's FTSE 100 blue-chip stocks index, after watching its shares plunge by almost 70 percent in a year.

Last week Man said its Head of Research Methodology Darren Upton, who led the team responsible for developing trading models for AHL, had left to join to ISAM, a rival company set up by former Man CEO Stanley Fink.

Man shares were trading down 0.6 percent at 72.4 pence by 0850 GMT, lagging a 0.1 percent drop in the FTSE All-Share index .FTAS.

Monday's announcement prompted concerns that Hayes' abrupt exit may trigger a fresh selloff from investors who have so far kept faith with Man despite watching its assets under management slide by more than $6 billion in the nine months to end-March.

CLIENT OUTFLOWS

Hayes himself had invested 88,100 pounds in 50,000 Man shares at 176.2 pence each in September, as two other senior executives also bought stock in a move seen at the time as an attempt to shore up confidence in the company following a surprise surge in client outflows in the previous quarter.

Man Chief Executive Peter Clarke said Sorrell had played an instrumental role in Man's recent takeover of FRM, a move welcomed by analysts as a way of reducing dependence on AHL, which accounts for roughly 70 percent of the group's revenue.

The $21 billion "black box" fund, named after 1980s founders Michael Adam, David Harding and Martin Lueck, is down an estimated 1.4 percent so far in 2012, after losing 6.4 percent last year.

It was around 14 percent away from its so-called high-water mark in March, the level at which it can start earning performance fees for Man.

"In his new position, Jonathan's experience in financial markets, especially his deep working knowledge of the hedge fund industry, will be extremely valuable as we continue to develop and evolve in challenging world markets," Clarke said.

Clarke said Sorrell would "bring clear focus on costs", but investors and analysts are hoping for a swift reversal in client outflows as well as greater financial efficiency.

Sorrell joined Man less than a year ago after a decade of service in the investment management and the securities and investment banking divisions at Goldman Sachs (GS.N), where he latterly led investments in a broad range of hedge fund firms.

(Editing by Anjuli Davies and David Holmes)

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