* The Toronto Stock Exchange's S&P/TSX composite index <.GSPTSE> ended the session down 69.94 points, or 0.44 percent, at 15,969.03.
* There were two decliners for every advancing stock and eight of the index's 10 main industry groups ended in the red.
* Shopify Inc <SHOP.TO>, down 6.3 percent at C$122.64, was among the heaviest weights on the index. The commerce software company has lost more than 17 percent of its value since hitting a peak on Cyber Monday, when it said its merchants had sold more than $1 billion of goods over the Thanksgiving shopping weekend.
* The energy group retreated 1.7 percent, as oil prices fell with the market eyeing signs of rising U.S. production. Suncor Energy Inc (>> Suncor Energy Inc.) fell 1.8 percent to C$43.76, as U.S. crude <CLc1> prices lost 1.6 percent to $57.45 a barrel, while Brent <LCOc1> shed 2 percent to $62.45. [O/R/]
* The largest percentage gainer on the TSX was uranium producer Cameco Corp (>> Cameco Corp), which surged 12.9 percent to C$13.59, while an uranium exploration company, NexGen Energy Ltd (>> Nexgen Energy Ltd), rose 16.5 percent to C$3.46 as the plans by Kazakhstan's state-run uranium mining company to cut production were expected to boost the price of the metal.
* The materials group, which includes precious and base metals miners and fertilizer companies, lost 1.2 percent.
(Reporting by Fergal Smith, editing by G Crosse)