TORONTO -- North American markets fell hard as Canada's main stock index posted its worst day in more than three years Wednesday, just two weeks after recording another large broad-based decline.

The S&P/TSX composite index closed down 2.5 per cent or 376.04 points to 14,909.13, marking the largest single-day decline since Sept. 1, 2015 and surpassing the 336.65 point drop on Oct. 10.

The decrease was led by the cannabis-heavy health-care sector, which fell 5.9 per cent. But it also included the heavyweight materials, financials, industrials and energy sectors, which together account for three-quarters of the Toronto Exchange.

"We're in a risk-off environment that's affecting all sectors except the safety sectors like utilities (while) telecom is down very modestly," says Anish Chopra, managing director with Portfolio Management Corp.

Although it's difficult to predict the market's future path, he said there is an environment of slower global growth amid an era of increasing tariffs.

"It's hard to make a really bullish case for the TSX unless you see large increases in the commodity price environment and the solution to the pipeline capacity issue out west," he said in an interview.

The triple-digit market slide came as the loonie traded higher in the wake of an interest rate hike by the Bank of Canada.

The Canadian dollar traded at an average of 76.75 cents US compared with an average of 76.35 cents US on Tuesday in the wake of the Bank of Canada's decision to raise its key interest rate by a quarter of a percentage point to 1.75 per cent.

In New York, American exchanges were walloped as they fell as much as 4.4 per cent.

The Dow Jones industrial average was down 608.01 points to 24,583.42. The S&P 500 index lost 84.59 points to 2,656.10, while the Nasdaq composite shed 4.4 per cent or 329.14 points to 7,108.40.

Chopra said investors on both sides of the border are focusing on rising interest rates, continuing trade tensions between China and the United States, Brexit and Italian budget woes.

"There tends to be a little bit of momentum to these risk-off environments so it's not like you'll just get one down day. There's a lot of investor concern about some of the macro issues and that's just carrying over from day to day," he said.

U.S. corporate earnings have been reasonable, he said, but investors are worried about whether they have reached a peak for this cycle.

"I think in Canada you're looking at a reasonable earnings season, somewhat similar to the U.S., but the concern is more as you get rate hikes...what will earnings be like a year out, two years out."

The December crude contract was up 39 cents at US$66.82 per barrel and the December natural gas contract was down 5.6 cents at US$3.23 per mmBTU.

The December gold contract was down US$5.70 at US$1,231.10 an ounce and the December copper contract was essentially unchanged at US$2.76 a pound.