Canada's main stock index fell on Wednesday as energy stocks weighed with a fall in oil prices and as uranium producer Cameco Corp plunged on a negative outlook.

Cameco fell 16.9 per cent to $14.39 after the company said it expected its 2016 adjusted profit to be significantly lower than analysts' estimates and also said it would cut 120 jobs at three of its uranium mines in 2017.

"The drop today certainly looks like an over-exaggeration to their announcement," said Michael Sprung, president at Sprung Investment Management Inc.

"There's more longer-term uncertainties out there that are worrying investors," he added, referring to political events south of the border. "For the time being we're going to be in a volatile market."

An interest rate cut remains on the table if the risks facing the country are realized, the Bank of Canada said, warning there would be "material consequences" if U.S. President-elect Donald Trump enacts protectionist policies.

The Toronto Stock Exchange's S&P/TSX composite index ended down 43.51 points, or 0.28 per cent, at 15,397.85.

Canada's biggest oil and gas producers weighed as oil prices fell to their lowest in a week on a strong U.S. dollar and expectations that U.S. producers would boost output even as OPEC's output fell from a record high.

Canadian Natural Resources Ltd fell 1.3 per cent to $40.60 and Suncor Energy Inc lost 0.7 per cent to $42.43. The energy group retreated 1.4 per cent overall.

"One thing that I think a lot of people have lost sight of is that the energy companies have been concentrating so much on their cost structure, they are much more efficient than they were," Sprung said.

The materials sector, which includes precious and base metals miners and fertilizer companies, fell 0.5 per cent.

Half of the index's 10 main groups were in negative territory, with five decliners for every two gainers. 

On Wall Street, the S&P 500 ended a choppy session slightly higher on Wednesday, helped by a rise in financials after Federal Reserve Chair Janet Yellen said it "makes sense" to gradually lift interest rates.

The S&P financials index rose 0.8 per cent, adding to gains late in the session following Yellen's remarks to the Commonwealth Club of California in San Francisco.

Financials have rallied since the November U.S. election on expectations of higher rates and of reduced regulations under President-elect Donald Trump.

Goldman Sachs was down 0.6 per cent and Citigroup fell 1.7 per cent, however. Both reported quarterly results earlier in the day.

The Dow ended lower for the fourth day in a row. The frenetic post-election rally in U.S. equities has slowed in recent weeks as investors wait for Trump to work on his campaign promises. Investors hope to get more insight following his inauguration on Friday.

"You might see people taking a break here and moving to the sidelines just to see what type of shape the environment takes as far as policy," said Michael O'Rourke, chief market strategist at JonesTrading in Greenwich, Connecticut.

The Dow Jones Industrial Average closed down 22.05 points, or 0.11 per cent, to 19,804.72, the S&P 500  gained four points, or 0.18 per cent, to 2,271.89 and the Nasdaq Composite added 16.93 points, or 0.31 per cent, to 5,555.65.

Qualcomm rose 1.5 per cent, helping boost the Nasdaq after Morgan Stanley said in a note the U.S. government may be reluctant to pursue an antitrust case against the company.

After the bell, shares of Netflix jumped eight per cent following its results, which showed international and U.S. subscriber additions well above analysts' estimates.

The pace of corporate results is expected to pick in the coming days. Analysts expect earnings from S&P 500 companies grew 6.3 per cent in the fourth quarter, which would be the biggest profit growth for the group in two years, according to Thomson Reuters data.

During the regular session, shares of Target fell 5.8 per cent after the brick-and-mortar chain reported dismal results for the holiday season and cut its quarterly earnings forecast. The S&P retail index was down 0.4 per cent.

Among other decliners, UnitedHealth was off 1.8 per cent at US$157.74 a day after reporting results.

Advancing issues outnumbered declining ones on the NYSE by a 1.15-to-1 ratio; on Nasdaq, a 1.28-to-1 ratio favored advancers.

The S&P 500 posted 13 new 52-week highs and four new lows; the Nasdaq Composite recorded 76 new highs and 27 new lows.

About 6.2 billion shares changed hands on U.S. exchanges, slightly above the 6.1 billion daily average for the past 20 trading days, according to Thomson Reuters data.