Dec 17 (Reuters) - Canada's main stock index extended gains for a third straight session on Thursday, as gold miner stocks gained, while hopes for fresh stimulus in United States further lifted sentiment.
* The materials sector .GSPTTMT , which includes precious and base metals miners and fertilizer companies, added 2.7% as gold futures GCc1 rose 1.2% to $1,878 an ounce. GOL/
* The sector's gains were led by the largest percentage gainers on the TSX, Seabridge Gold Inc SEA.TO and MAG Silver Corp MAG.TO , which jumped 5.2% and 4.5% respectively.
* At 9:37 a.m. ET (14:37 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was up 98.08 points, or 0.56%, at 17,665.5.
* The optimism in the Canadian market followed the upbeat rally across global markets after U.S. congressional leaders sounded more positive about a $900 billion stimulus package.
* Adding to the upbeat mood, the energy sector .SPTTEN climbed 0.1% as U.S. crude CLc1 prices rose 1.0% a barrel, while Brent crude LCOc1 added 0.7%. O/R
* On the TSX, 149 issues advanced, while 66 issues declined in a 2.26-to-1 ratio favoring gainers, with 16.15 million shares traded.
* Aurinia Pharmaceuticals Inc AUP.TO fell 9.7%, the most on the TSX, after the biotech firm announced a licensing agreement with Otsuka Pharmaceutical Co Ltd.
* The second biggest decliner was pot producer Aphria Inc APHA.TO , down 5.8%, after brokerage Stifel downgraded it to "hold" from "buy".
* The most heavily traded shares by volume were BCE Inc BCE.TO , Canadian Imperial Bank of Commerce CM.TO , and Air Canada AC.TO .
* The TSX posted six new 52-week highs and no new low.
* Across Canadian issues, there were 74 new 52-week highs and four new lows, with total volume of 32.55 million shares.