The drop in the $900 million Gold Fund, which invests in bullion-related equities and derivatives, brings its 2013 loss to 26 percent, Paulson & Co. said in the update. The firm’s Advantage funds fell in February after the metal declined 5.1 percent and related stocks slumped 10 percent in the month as signs of economic optimism curbed demand for gold as a haven.

All of the gold share classes of Paulson & Co.’s funds posted declines in February, the New York-based firm said in the update. Investors can choose between gold- and dollar-denominated versions of most of Paulson’s funds. About 55 percent of the firm’s investors and 85 percent of Paulson’s money are in the gold share classes, the fund manager said last month at the EnTrust Investor Summit in New York.

“Despite the volatility and drawdown of our gold equity positions, we believe in the long-term outlook for these positions as quantitative easing programs continue around the world, credit expands in the United States, and gold equities continue to trade at a significant discount to historical average evaluations,” the firm said in a letter sent to clients, a copy of which was obtained by Bloomberg News.

Paulson & Co.’s dollar-denominated Recovery, Credit Opportunities and merger-themed Partners funds all posted gains in February.

Armel Leslie, a spokesman for $18 billion Paulson & Co., declined to comment on the returns.