Chairman of Soros Fund Management, USA, George Soros, speaks at the Seehof hotel on the sidelines of the World Economic Forum in Davos, Switzerland on Jan. 26, 2011. (Michel Euler/AP)

Soros, who turns 81 next month, will return $1 billion to outside investors in his $25.2 billion firm, marking the end of a four decade-long career as a hedge-fund manager.

Soros will continue to manage and invest his own money as a family office. The firm’s chief investment officer will also leave.

Bloomberg reports “the move completes Soros’s transformation from a speculator, who in 1992 made $1 billion betting that the Bank of England would be forced to devalue the pound, to philanthropist statesman, a role he first imagined for himself as a Hungarian emigre studying at the London School of Economics after World War II.”

Over the past 30 years, Soros has given away more than $8 billion to promote democracy, improve education, foster free speech, and fight poverty around the world.

Soros’s sons said they made the decision because of new financial regulations, which would have required the firm to register with the Securities and Exchange Commission by March 2012 if it wanted to continue managing money for outsiders. The firm said it now made more sense to run it as a family office.

Soros himself did not comment on the news.

Soros is one of many wealthy and well-known fund managers to retire in response to the regulations, including Carl Icahn and Soros' former deputy Stanley Druckenmiller, who Reuters writes “are deciding that managing money for others may create more headaches than necessary.”

Business Insider speculated that “it also helps explain (perhaps) [Soros’] big move to cash recently,” with one of Soros’s funds, the flagship Quantum Endowment Fund, reported to be holding 75 percent cash on July 17.

A trader in Chicago tweeted in response to the news:

For those that were emulated Soros and went to cash, are you retiring too?less than a minute ago via Echofon Favorite Retweet ReplyEli Radke

Others made predictions:

Quantum’s Soros is calling it quits. Since Quantum is 75% cash, this decision will not impact the markets too heavily.less than a minute ago via web Favorite Retweet ReplyEconomic Forecast

And many referenced Glenn Beck, who has repeatedly called Soros a “puppet master” and leader of a group of left-wing people who want to replace the current geopolitical system with a “new world order”:

curious to hear why soros is REALLY quitting his hedge fund. listening to @glennbeck to find out now!less than a minute ago via TweetDeck Favorite Retweet Replyscarnsworth