Gold prices fell for a sixth straight day Thursday. Gold closed at its lowest level since a late-summer rally began.

Gold has fallen almost 5 percent since Dec. 20. It's down 11 percent this month.

The February gold contract fell $23.20, or 1.5 percent, to $1,540.90 an ounce. That's the lowest closing price since July. Gold prices surged in August as worries mounted that recession would strike Europe and central banks around the globe might respond by printing more money or lowering interest rates. Many investors bought gold as a way to protect against inflation.

Many traders think gold has become overpriced. Gold was trading near $1,900 an ounce as recently as September. Now a growing U.S. economy has lured traders to put money back into riskier investments like stocks.

In other trading, industrial metals palladium and platinum fell. Copper edged higher.

Copper for March delivery gained 0.45 cents to $3.37 per pound. March palladium lost $23.40 to $623.75 an ounce. January platinum fell $25.60 to $1,366.80 an ounce.

Crop prices fell.

March wheat dropped 6 cents to finish at $6.4525 per bushel. March corn fell 4.5 cents to $6.38 per bushel.

January soybeans fell 11 cents to $11.97 per bushel.

Benchmark crude oil gained 29 cents to finish at $99.65 per barrel on the New York Mercantile Exchange. Heating oil rose 1.89 cents to end at $2.9201 per gallon, gasoline futures rose 2.38 cents to $2.6694 per gallon and natural gas lost 9.3 cents to $3.055 per 1,000 cubic feet.