At 9:34 a.m. ET (1334 GMT), the Toronto Stock Exchange's S&P/TSX Composite index was down 31.8 points, or 0.19pc, at 16,431.15.

The materials sector, which includes precious and base metals miners and fertilizer companies, lost 0.4pc, the most on the TSX.

Gold prices dropped below $1,400 as the dollar rallied on expectations of a less dovish US Federal Reserve ahead of testimony from the chairman of the central bank.

The financials sector slipped 0.3pc. The industrials sector fell 0.1pc.

Investors are also looking ahead for a key interest rate announcement by the Bank of Canada on Wednesday, where the central bank is widely expected to keep rates on hold at least through this year.

On the TSX, 79 issues were higher, while 138 issues declined for a 1.75-to-1 ratio to the downside, with 6.87 million shares traded.

The biggest percentage gainers on the TSX were Richelieu Hardware Ltd, which jumped 1.2pc followed by shares of Genworth MI Canada, which rose 1pc.

Canntrust Holdings fell 4.4pc, the most on the TSX, followed by shares of First Quantum Minerals, down 3.9pc.

The most heavily traded shares by volume were Canntrust and Trevali Mining.

The TSX posted one new 52-week high and two new lows.

Across all Canadian issues there were five new 52-week highs and five new lows, with total volume of 13.42 million shares.