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TSX down 0.5% at 21,880.95

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Posts its lowest closing level since June 28

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Materials group falls 3.1%; metal prices decline

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Shopify ( SHOP ) surges 17.9% after Q2 revenue beat

(Updates at market close)

By Fergal Smith

Aug 7 (Reuters) - Canada's main stock index fell to a

near six-week low on Wednesday, including declines for metal

mining shares, as investors eyed numerous challenges to the

market outlook and despite a sharp increase in the shares of

Shopify ( SHOP ).

The Toronto Stock Exchange's S&P/TSX composite index

ended down 98.41 points, or 0.5%, at 21,880.95, its

lowest closing level since June 28.

It was the fourth straight day of declines for the index,

the longest daily losing streak since April, after an earlier

attempt to rally petered out.

"Over the next six weeks, I think it's going to be very

challenging for this market to keep either volatility down, or

to stay on a bid," said Paul Gardner, partner & portfolio

manager at Avenue Investment Management. "There are just a lot

of negative forces that are hitting the market."

Winding down of yen-funded carry trades and concern the

Federal Reserve has waited too long to cut U.S. interest rates

have been among the headwinds for the market in recent days.

U.S. stocks also ended lower, with investor jitters stoked

by weak demand in a 10-year Treasury auction.

The materials group, which includes metal miners and

fertilizer companies, lost 3.1% as gold and copper

prices fell.

The consumer staples sector was down 1.5% and heavily

weighted financials ended 1.1% lower.

Technology was a bright spot, adding 3.3%, as the shares of

Shopify Inc ( SHOP ) surged 17.9% after the e-commerce company

beat analysts' estimates for second-quarter revenue.

Energy shares also advanced, adding 1.3%, as the price of

oil settled 2.8% higher at $75.23 a barrel after data

showed a bigger-than-expected draw in U.S. crude stockpiles.

Suncor Energy Inc ( SU ) was up 4.4% after the oil producer

beat quarterly earnings estimates.