Billionaire investor George Soros believes the current financial crisis is the worst since the Great Depression, and said stocks have not bottomed yet, Bloomberg News reported Thursday.

Soros said the most recent market bottom "will probably not prove to be the final bottom," adding that the current stock rebound will last six weeks to three months as the United States moves closer to recession, Bloomberg News reported.

Further, Soros, in an op-editorial column in The Financial Times, argued that the cause of the market's current problems is a flawed premise: the belief that markets are self-correcting and tend toward equilibrium. They aren't and don't, Soros argues, and the laissez-faire policy creates bubbles, including the most-recent housing bubble, which, in turn, when it started to burst, led to the current credit crunch.

Soros cites deregulation

Soros added that the market's current troubles originated in 1980 when U.S. President Ronald Reagan and United Kingdom Prime Minister Margaret Thatcher led a laissez-faire movement that reduced/eliminated regulation of banks and financial markets, the FT reported.