Sept 18 (Reuters) - Canada's main stock index looked set to snap a six-day winning streak on Wednesday, as the energy and materials sectors posted some of the biggest losses.
* At 9:36 a.m. ET (1336 GMT), the Toronto Stock Exchange's S&P/TSX Composite index .GSPTSE was down 19.11 points, or 0.11%, at 16,815.64.
* Nine of the index's 11 major sectors were lower.
* The energy sector .SPTTEN dropped 0.7% as oil prices extended their decline after Saudi Arabia said it would quickly restore full production following last weekend's attacks on its facilities. O/R
* U.S. crude CLc1 prices were down 1.7% a barrel, while Brent crude LCOc1 lost 1%.
* The materials sector .GSPTTMT , which includes precious and base metals miners, lost 0.6% as copper prices fell on Wednesday as concern about demand and economic growth dominated sentiment. MET/L
* Canada's annual inflation rate fell slightly in August on lower gasoline prices, Statistics Canada said on Wednesday in its first major data release since Canadian politicians formally hit the campaign trail. Trading environment also remained tepid as investors awaited an interest rate decision from the U.S. Federal Reserve.
* On the TSX, 80 issues were higher, while 141 issues declined for a 1.76-to-1 ratio to the downside, with 10.79 million shares traded.
* The largest percentage gainers on the TSX were shares of Interfor Corp IFP.TO , which climbed 2.7%, followed by shares of West Fraser WFT.TO , which rose 2.4%.
* CannTrust Holdings TRST.TO fell 6.5%, the most on the TSX, after regulator Health Canada suspended the company's license to produce and sell cannabis.
* The most heavily traded shares by volume were CannTrust, Crescent Point CPG.TO , and Encana Corp ECA.TO .
* The TSX posted three new 52-week highs and one new low.
* Across all Canadian issues there were 18 new 52-week highs and two new lows, with total volume of 16.49 million shares.