(Bloomberg News) Hedge funds raised bets on higher commodity prices for the first time in six weeks, just before the biggest three-day slump since October as U.S. jobs data fell short of expectations and European manufacturing contracted.

Money managers increased net-long positions across 18 U.S. futures and options by 6.9 percent to 895,240 contracts in the week ended May 1, the biggest gain since Feb. 28, Commodity Futures Trading Commission data show. Bullish copper wagers surged sevenfold before prices fell for three days, and soybean bets reached the highest since at least June 2006 as the oilseed capped the biggest weekly loss since mid-January.

The Standard & Poor's GSCI Spot Index of 24 raw materials tumbled 4.9 percent in the three sessions ended May 4, the most since Oct. 4. Reports showed last week that services and manufacturing output shrank last month in the euro region and the U.S. added fewer jobs than forecast in April. Open interest, or contracts outstanding, across commodities fell 2 percent in the seven sessions through April 30, the longest slide since November, data compiled by Bloomberg show.

"We had some soft data points along the edges that's taken some of the steam out of the market," said Kelly Wiesbrock, who helps manage $1.3 billion of assets for San Francisco-based hedge fund Harvest Capital Strategies. "It's hard to know whether this is a just a little bit of a pause, or if this is something bigger."

Prices Slide

The S&P GSCI plunged 4.5 percent last week, the most since Dec. 16. The MSCI All-Country World Index of equities dropped 2.3 percent, and the dollar rose 1 percent against a basket of six major currencies. Treasuries returned 0.3 percent, a Bank of America Corp. index shows.

The GSCI extended its drop today, falling 1.1 percent to 646.62 at 11:04 a.m. in New York. The gauge is headed for a fourth straight decline, which would be the longest slide since August.

Twenty-two of the raw materials tracked by the S&P GSCI declined last week. Gasoline plunged 7.2 percent, copper dropped 2.7 percent and soybeans fell 1 percent. On May 4, crude oil slumped below $100 a barrel for the first time since February.

Payrolls in the U.S. rose 115,000 in April, the smallest gain in six months, the Labor Department said May 4. That compared with the median estimate of 160,000 in a Bloomberg survey of 85 economists. Unemployment in the 17 countries that use the euro rose to a 15-year high and manufacturing contracted for a ninth month, reports from the European Union's statistics office and Markit Economics on May 2 showed. European Central Bank President Mario Draghi said May 3 that the economic outlook has become "more uncertain."

Chinese home prices fell to a 14-month low in April, SouFun Holdings Ltd., the nation's biggest real-estate website owner, reported May 2. The country is the biggest buyer of everything from copper to cotton to soybeans.