Lou Simpson, a fund manager for Warren Buffett, plans to retire at the end of the year from his post at Berkshire Hathawayâ??s Geico subsidiary.

Mr Simpson, who was once tipped as a potential successor to Mr. Buffett, is currently chief executive for capital operations of Geico, the car insurer that Mr Buffettâ??s Berkshire Hathaway has wholly owned since 1996, and oversees its $4bn investment portfolio.

Over his 30 years with Geico, Mr Simpson built a reputation by outperforming the S&P 500 in 18 of the years between 1980 and 2004, the last year when Geicoâ??s individual investment performance was reported.