Billionaire investor George Soros' hedge fund more than doubled its bet on the price of gold during the fourth quarter, a portion of the firm's total U.S.-listed equity holdings of $8.8 billion at the end of 2009.

The New York-based firm also disclosed in a filing on Tuesday with the U.S. Securities and Exchange Commission that it bought almost 95 million shares of Citigroup during the quarter, worth $313 million by the end of the year. Soros reported no holdings of the troubled bank's shares at the end of the third quarter.

Soros Fund Management owned 6.2 million shares of SPDR Gold Trust -- an exchange-traded fund that owns gold bullion -- at the end of the year worth $663 million. That was up from 2.5 million shares at the end of the third quarter.

Soros and other noted investors like John Paulson have previously touted gold as a hedge against inflation, further economic turmoil or a decline in the value of the U.S. dollar. Last month at the World Economic Forum in Davos, Soros said the ultimate asset bubble is gold, but he declined to say whether he was investing in the precious metal.

The filing for the end of the fourth quarter revealed no listing for Canadian chemicals manufacturer Potash Corp of Saskatchewan

, Soros' largest holding at the end of the third quarter.

That could indicate that the almost 3 million share investment was sold during the fourth quarter. But large investors occasionally leave off major holdings when they are trading the position and disclose their investment in a confidential filing with the SEC or in a subsequent amendment to their public report.

The firm does not comment on its holdings, a spokesman said.

Soros' most recent SEC filing also revealed large bets on seed producer Monsanto and Brazilian gas and oil giant Petroleo Brasileiro SA

, also known as Petrobras.

The firm held 3.9 million shares of Monsanto at the end of the fourth quarter, up from 1.1 million three months earlier.

Soros also reported a stake of 7.7 million shares of Petrobras's U.S. ADRs, worth $369 million, and a slight increase from the 7.4 million receipts held at the end of the third quarter. Soros had another 5.9 million shares of nonvoting ADRs worth $249 million, virtually unchanged from his holding three months earlier.

Soros also reported raising his holdings in oil company Hess Corp and telecommunications company AT&T Inc among others.

According to the regulatory filing, Soros Fund Management raised its holding in carmaker Ford Motor Co to 10.9 million shares from 7.3 million shares at the end of the third quarter, when Soros started to accumulate his position.

Soros also raised his holdings of AT&T for the second straight quarter to 4.7 million shares at the end of the fourth quarter from 4.2 million shares at the end of the third quarter.

Large investors such as Soros are required to report holdings of U.S.-listed equities at the end of each quarter, but not short positions or holdings of other securities like bonds and over-the-counter derivatives contracts. Investors are also allowed to file some holdings on confidential reports if they are trading into or out of a position at the end of a quarter.

(Reporting by Aaron Pressman, Ros Krasny and Svea Herbst-Bayliss; Editing by Andre Grenon, Steve Orlofsky and Phil Berlowitz)