TORONTO (Reuters) - The Toronto Stock Exchange's main index trimmed losses but ended lower yesterday due to a sell-off in financial and materials shares as commodity prices fell and quarterly results from two major banks disappointed.

It was the third session in a row that the index has finished negative, but late in the day it pulled away from earlier losses of more than 200 points.

The index's materials sector slid 1.8 percent, while that sector's gold producers sub-index gave up 3.1 percent, hurt by profit-taking after a strong surge the previous session.

Tumbling gold prices also pressured the resource shares as a fall in crude oil prices pulled spot gold off recent highs.

In Toronto, Barrick Gold was down C$2.02, or 3.8 percent, at C$50.90, and Kinross Gold gave up C$1.04, or 4 percent, to C$24.86.

Bank of Montreal lost C$1.47, or three percent, to C$46.89 after the bank reported a worse-than-expected drop in profit, stung by writedowns related to the capital market and rising provisions for bad loans.

Bank of Nova Scotia tumbled after its earnings fell just shy of what the Street expected, as it was also hurt by credit market-related charges and higher loan-loss provisions.

Scotiabank finished down 91 Canadian cents, or two percent, at C$45.59.

The financial sector as a whole was down 0.7 percent.

The S&P/TSX composite index closed down 67.57 points, or 0.5 percent, at 13,476.81 with six of its 10 main sectors lower.

Talk of a rescue plan for US bond insurer Ambac Financial Group Inc., as well as covering by investors who have short positions in the market, helped lift the index late in the afternoon, said Sal Masionis, stockbroker at Brant Securities.

As well, the commodities sector managed the edge up 0.2 percent, bouncing back from earlier losses as oil prices fell amid rising US inventories.

Suncor Energy was up 94 Canadian cents, or 0.9 percent, at C$104.81, and Imperial Oil Ltd rose C$1.02, or 1.9 percent, to C$55.87.