Hedge funds cut bullish commodity bets to a six-month low as mounting concern that slowing economic growth will erode demand drove prices toward the first fourth-quarter retreat since the global recession.

Speculators reduced net-long positions across 18 U.S. futures and options by 11 percent to 675,625 million contracts in the week ended Dec. 24, the lowest since June 19, U.S. Commodity Futures Trading Commission data show. Gold holdings reached a four-month low, while those for copper dropped for the first time in five weeks. Investors are the most bearish on natural gas since May.