July 23 (Bloomberg) -- Commodity traders increased bets on price gains for raw materials by 50 percent in the past two weeks at futures exchanges in New York and Chicago. Hedge-fund managers and other large speculators held net- long position in gold, copper, crude oil and 17 other commodities totaling 782,247 contracts in the week ended July 20, according to data from the U.S. Commodity Futures Trading Commission compiled by Bloomberg. That compares with 520,530 contracts in the week ended July 6. The 50 percent gain was the biggest two-week jump since May 2009. The Reuters/Jefferies CRB Index of 19 raw materials rallied 1.7 percent this week, the third straight gain, as rising corporate earnings signaled resilient economic growth and robust demand for energy, metals and grains. Open interest in futures tracked by the CRB increased 1.2 percent this week, the most since April 9. --Editors: Steve Stroth, Patrick McKiernan. To contact the reporter on the story: Millie Munshi in New York at mmunshi@bloomberg.net; Patrick McKiernan in New York at pmckiernan@bloomberg.net.

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