The Toronto Stock Exchange's  S&P/TSX fell 104.14 points, or 0.64 percent, to 16,193.41.

Leading the index were WestJet Airlines Ltd, up 59.9 percent, Pretium Resources Inc, up 7.2 percent, and Alamos Gold Inc, higher by 7 percent.

Lagging shares were Canopy Growth Corp, down 7.5 percent, Hexo Corp, down 7.2 percent, and Sierra Wireless Inc, lower by 6.9 percent.

On the TSX 100 issues rose and 141 fell as a 0.7-to-1 ratio favored decliners. There were 9 new highs and 8 new lows, with total volume of 229.5 million shares.

The most heavily traded shares by volume were Enbridge Inc, Westjet Airlines Ltd and Manulife Financial Corp.

The TSX's energy group fell 3.51 points, or 2.3 percent, while the financials sector slipped 3.38 points, or 1.1 percent.

West Texas Intermediate crude futures fell 1.38 percent, or $0.84, to $60.81 a barrel. Brent crude  fell 1.06 percent, or $0.75, to $69.87 [O/R]

The TSX is up 13.1 percent for the year.