New York money manager John Paulson made a billion dollars on the money markets in a few months over the summer.

The windfall meant he entered the list of the top 400 wealthiest Americans at number 165 - equal with Oprah Winfrey.

They both have fortunes of £1.25billion.

Last night some analysts criticised Mr Paulson for cashing in on the plight of ordinary Americans.

Others said he was simply a businessman who saw an opportunity and took advantage of it.

"He gambled big," one said.

"If things had gone the other way, he'd be bankrupt now."

Mr Paulson, 51, a former partner in the Bear Stearns international investment bank, runs his own company, the Paulson Hedge Fund.

Such funds are basically huge pots of private money given by wealthy investors to one manager to wheel and deal on the financial markets in the hope of making big profits.

Because they are private, they operate in great secrecy with fewer legal restrictions than other investment funds.