* TSX down 128.31 points, or 0.84 percent, to 15,219.03
* Nine of the index's 10 main groups were lower
By Solarina Ho
TORONTO, April 30 (Reuters) - Canada's main stock index fell on Thursday as investors, positioning their portfolios at the end of the month, appeared less than impressed by a slew of quarterly results.
Goldcorp Inc, the world's biggest gold producer by market value, saw its first-quarter profit fall due in part to lower margins on gold sales and a higher tax rate. It was the most influential decliner on the index, falling 5.37 percent to C$22.91.
Potash Corp, which missed quarterly forecasts and also cut its full-year profit outlook, declined 1.6 percent to C$39.17.
Suncor Energy Inc fell 1.22 percent to C$39.39 after it reported a quarterly loss on Wednesday due to lower crude prices and a foreign exchange loss.
BCE Inc, which reported a modest first-quarter adjust profit, dipped 0.83 percent to C$53.70.
At 10:54 a.m. EDT (1454 GMT), the Toronto Stock Exchange's S&P/TSX composite index slumped 131.07 points, or 0.85 percent, to 15,216.27.
"Pretty ugly today. Sour moods out in the markets," said Barry Schwartz, portfolio manager at Baskin Financial Services.
"We've had a pretty good start to the year for the Toronto market. It's beaten some of the other U.S. indices and it's having a pretty good month. End of the month can always be wacky and weird and people are positioning their portfolios," he said.
Declining issues outnumbered advancing ones on the TSX by 212 to 32, for a 6.63-to-1 ratio on the downside. Of the index's 10 main groups, all but healthcare were in retreat.
The hefty financials group was down 0.8 percent, with Royal Bank of Canada off 0.9 percent at C$80.22.
The materials group, home to mining and other resource companies, retreated 1.7 percent. Barrick Gold Corp declined 2.9 percent to C$15.75.
Gold futures fell 2.4 percent to $1,180.6. after upbeat U.S. jobless claims data boosted the U.S. dollar.
Reporting by Solarina Ho; Editing by Meredith Mazzilli