One of the world's best known investment managers, George Soros, says he plans to stop managing other peoples' money by the end of the year and return nearly a billion dollars to investors.

Soros, who turns 81 next month, told outside investors in his $25 billion Quantum fund on Tuesday that he plans to continue to manage family assets while returning money to outsiders. The fund's co-deputy chairmen, Soros's sons Jonathan and Robert, said the action is being taken to avoid new U.S. financial regulations that would have forced the fund to register with the Securities and Exchange Commission by next March if it continued to manage outside assets.

Over the years, the elder Soros has transformed himself from a speculator who made $1 billion in 1992 betting that the Bank of England would be forced to devalue the pound, to one of the world's foremost philanthropists. He has given away more than $8 billion of his fortune to promote democracy and free speech, as well as improving education and fighting poverty around the world.

Soros has also become a financial fixture in U.S. political circles, frequently helping fund the campaigns of Democratic politicians and liberal causes.

Soros is a native of Hungary, studied at the London School of Economics after World War Two and has lived in New York for decades.