Half the index's 10 main groups finished in negative territory, with decliners outnumbering advancers by almost 2-to-1 overall. The energy group fell 2.3 percent, as oil prices retreated from highs last seen in 2015. Canadian Natural Resources Ltd fell 2.5 percent to C$45.36 and Suncor Energy Inc was off 1.5 percent at C$46.93.
The materials group, which includes precious and base metals miners and fertilizer companies, lost 0.9 percent, with Barrick Gold Corp down 1.3 percent at C$18.55 as gold prices also dipped after a recent rally. The two natural resource sectors combine to account for more than 30 percent of the index's weight.
Brookfield Business Partners LP gained 5 percent to C$47.35 after saying it planned to buy Westinghouse Electric Co from Toshiba Corp for $4.6 billion. Its parent company, Brookfield Asset Management Inc, slipped 0.8 percent to C$54.16. Marijuana producers fell early before turning higher in heavy volumes. They had been rising sharply over the last week but were hit hard on Thursday when the US federal government rescinded a policy that had eased enforcement of federal marijuana laws.
Canopy Growth Co finished up 5.2 percent at C$34.00 and Aphria Inc gained 3.6 percent to C$19.16. Aurora Cannabis Inc rose 2.4 percent to C$13.35 after announcing its second investment in as many days.