(Adds sector details; updates prices)
Dec 18 (Reuters) - Canada's main stock index shed initial gains on Friday to snap its three-day winning streak due to weakness in materials sector, while strength in energy stocks and upbeat domestic retail sales data helped limit losses.
* The materials sector .GSPTTMT , which includes precious and base metals miners and fertilizer companies, lost 1.1% as Spot gold XAU= fell 0.1% to $1,884.71 per ounce, retreating from a one-month peak scaled in the last session. GOL/
* At 09:41 a.m. ET (14:41 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 39.46 points, or 0.22%, at 17,613.48.
* BlackBerry Ltd BB.TO fell 6.6%, the most on the TSX, after the cybersecurity firm missed Wall Street estimates for third-quarter revenue. The second biggest decliner was Enghouse Systems Ltd ENGH.TO , down 3.5%.
* The energy sector .SPTTEN climbed 0.6% as U.S. crude CLc1 prices were up 0.8% a barrel, while Brent crude LCOc1 added 0.6%. O/R
* Canadian retail sales grew 0.4% to $54.59 billion ($42.65 billion) in October, led by motor vehicle and parts dealers, Statistics Canada said. The financials sector .SPTTFS slipped 0.1%, while the industrials sector .GSPTTIN rose 0.2%.
* On the TSX, 66 issues advanced, while 148 issues declined in a 2.24-to-1 ratio favoring losers, with 104.13 million shares traded.
* The largest percentage gainers on the TSX were media company Corus Entertainment Inc CJRb.TO that added 3.2%, and uranium producer Cameco Corp CCO.TO that rose 2.8%.
* The most heavily traded shares by volume were Toronto-Dominion Bank TD.TO , Royal Bank of Canada RY.TO , and Enbridge Inc ENB.TO .
* The TSX posted five new 52-week highs and no new low.
* Across Canadian issues, there were 81 new 52-week highs and three new lows, with total volume of 120.84 million shares.