Standard & Poor’s said its commodity index declined 7.9 percent in January, with all the sectors performing poorly due to concerns about the sluggish U.S. economy recovery.

“Fears of potential economic weakness, as well as some reversion of the substantial asset rallies seen in 2009, were certainly at play in January,” says Michael McGlone, director of Commodity Indexing at S&P GSCI.

The decline in January coincided with a 3.6 percent loss for the S&P 500, a 2.1 percent increase in the U.S. dollar index and a 32 basis point decline on the yield of the benchmark two-year Treasury note.

Investors typically shift their money to Treasuries when they feel equities and commodities are too risky.

The metals sector was the hardest hit in January, falling 8.9 percent after registering an 82.4 percent gain in 2009. The energy sector fell 8.6 percent, while agricultural sector fell 7.2 percent.

Agricultural commodities were also pressured in January after a crop report from the U.S. Department of Agriculture indicated a surprisingly abundant U.S. harvest despite challenging weather conditions.

On the positive side, soft commodities bucked the trend. Led by sugar, the soft commodity sub-index gained 3.5 percent during the month, and has now posted a 12-month return of 46.7 percent.