Crude oil wiped out all of its gains for 2011 and natural gas traded below $4 for the first time since April in New York as concern the global economy is weakening sent raw materials prices tumbling around the world.

All 24 commodities on the Standard & Poor’s GSCI Index declined slipped, as a rout in equities drove the Standard & Poor’s 500 Index to its worst nine-day slump since March 2009. Silver dropped 6 percent, gold retreated from a record and wheat slumped the most since June.

“There’s a lot of pessimistic news on the macro-economic front and that’s hitting commodities,” said Michael Wittner, the head of oil-market research at Societe Generale SA in New York and the fourth-most-accurate forecaster for West Texas Intermediate oil among 26 analysts ranked by Bloomberg in the past eight quarters. “If the economy continues to slow, demand for oil will take a hit.”

U.S. consumer confidence dropped last week to the lowest level in more than two months, paced by growing dissatisfaction among women and high earners, a report today showed. The Bloomberg Consumer Comfort Index was minus 47.6 in the period to July 31, the lowest level since May, compared with minus 46.8 the prior week.