Man, which started life as a rum supplier to the British Navy before morphing into a complex money manager, saw its shares shoot up nearly six per cent in afternoon trading as investors cheered the shake-up.
The company has been stricken by a large loss of business and a tumbling share price over the past 12 months, forcing many investors away from the firm.
Clarke will retire from the business on 28 February with Roman, current president and chief operating officer and a former Goldman Sachs derivatives boss, taking the helm.
Roman said: “These are tough times for the asset management industry, as for many parts of financial services.”
He added Man would be “intensifying” its focus on fund performance during his regime.