TORONTO (Reuters) - The Toronto Stock Exchange's main index snapped its six-day winning streak and closed slightly lower yesterday, hurt by softer commodities and recurrent worries over the impact of the economic slowdown south of the border.

Shares of gold producers lost 1.7 percent as the price of bullion was stung by profit-taking.

Barrick Gold was among the day's biggest weighted decliners, giving up C$1.09, or 2.4 percent, to C$43.60, while Goldcorp was down 92 Canadian cents, or 2.3 percent, at C$40.03.

Shares of other resource companies offset some of the losses, including Potash Corp of Saskatchewan, which was up C$2.62, or 1.5 percent, at C$178.27, and Fording Canadian Coal Trust , which rose C$4.37, or 7.1 percent, to C$65.63. The materials sector as a whole edged down 0.2 percent.

Analysts said overall sentiment was shaken by a report from the International Monetary Fund that forecast writedown losses related to the credit squeeze could reach $945 billion.

As well, the earnings season got off to a weak start with a disappointing quarterly profit from Alcoa on Monday night.

Gavin Graham, chief investment officer at Guardian Group of Funds, said that along with soft oil and gold prices, which are major drivers for the resource-heavy TSX, the "reminder that things are not great in the States" helped pull the Toronto index down.

"I think you got a bunch of really lousy first-quarter results out of the States, starting with Alcoa, so it's difficult to get too enthused when it's very obvious exactly how bad things are south of border," Mr. Graham said.

The S&P/TSX composite index closed down 17.48 points, or 0.13 percent, at 13,727.53 with seven of its 10 main sectors lower and one flat.

Banking issues gave up 0.7 percent amid fresh trouble in the financial markets as US savings and loan Washington Mutual said it expects a quarterly loss of $1.1 billion, while it secured a $7 billion capital injection.

In Toronto, Canadian Imperial Bank of Commerce was off 90 Canadian cents, or 1.3 percent, to C$68.00, while Bank of Nova Scotia dipped 46 Canadian cents, or one percent, to C$46.66.

Research In Motion was among the biggest lifts on the benchmark with the maker of the BlackBerry rising C$2.60, or 2.2 percent, to C$122.58.

The energy sector managed to eke out a gain of 0.4 percent even though crude prices weakened. Imperial Oil moved up C$1.11, or 2.1 percent, to C$54.80, and Canadian Natural Resources added C$1.35, or 1.8 percent, to C$75.03.

The only other sector on the upside was the small utilities group, which was up 0.4 percent, while the industrials sector was flat.