Gold, which has risen in each of the last three weeks, is already up 8.6 percent in July and appears poised for its biggest monthly improvement since January 2012. But at least one big investment bank is warning that the gains won't last.

Last week gold climbed 2.2 percent to finish at $1,321.90 an ounce on the Comex in New York, its third consecutive weekly gain. On Monday the yellow metal advanced to $1,329.40. Hedge funds raised wagers on a gold rally as speculation that the Federal Reserve will hold off on curbing stimulus drove prices toward the biggest gain in 18 months, according to a report by Bloomberg on Monday.

Goldman Sachs (NYSE: GS) expects the rally to reverse, and National Securities Corp. sees a limit to the current rally.

“Gold has made a terrific recovery, but there’s going to be resistance from people who got caught before, so there’s not too much to the upside for now,” said Donald Selkin, who helps manage about $3 billion of assets as the New York-based chief market strategist at National Securities Corp. “People are going to wait and see what the Fed is going to do.”