TORONTO -- Canada's main stock index dipped for a third straight day as investors responded to reports that an interim U.S.-China trade deal may not be completed this year.

"It's pretty obvious the market has been focusing on that and it's a narrative that can change daily and even hourly with those negotiations," said Kevin McLachlan, portfolio manager at Fiduciary Trust Canada.

The S&P/TSX composite index closed down 5.58 points at 17,005.82, after hitting an intraday low of 16,962.61.

In New York, the Dow Jones industrial average lost 112.93 points at 27,821.09. The S&P 500 index was down 11.72 points at 3,108.46, while the Nasdaq composite was down 43.93 points at 8,526.73.

North American stock markets have fallen from record highs after soaring on the Oct. 11 announcement that the world's two largest economies had reached a partial trade deal.

Also contributing to Wednesday's softness was the release of Federal Reserve minutes from its October meeting that reiterated its stance to probably not further lower interest rates for the foreseeable future, McLachlan added in an interview.

"While it's no surprise, the equity markets tend to like lower rates so that may be contributing to the selloff."

The Canadian dollar fell to its lowest level in about six weeks by trading at 75.17 cents US compared with an average of 75.55 cents US on Tuesday.

The loonie decreased as the price of Western Canadian Select crude oil prices dropped amid a CN Rail strike that is reducing movements of crude by rail. Meanwhile, West Texas Intermediate prices were pushed higher by a drop in U.S. stockpiles.

The January crude contract was up US$1.66 at US$57.01 per barrel and the January natural gas contract was up 3.5 cents at US$2.61 per mmBTU.

The key health care sector rose 3.8 per cent on substantial gains by the cannabis sector led by the Green Organic Dutchman Holdings, Canopy Growth Corp. and Aurora Cannabis Inc. whose shares increased 21.9, 15.7 and 12.5 per cent respectively.

Materials was marginally higher even though gold prices dipped.

The December gold contract was down 10 cents at US$1,474.20 an ounce and the December copper contract was down 0.7 of a cent at US$2.65 a pound.

Industrials was the weakest sector on the day, pushed down by CN Rail, whose shares fell 1.8 per cent during the second day of its national strike.