Canada’s main stock index headed lower Tuesday as oil prices reversed course and fell after four straight days of gains.

The Toronto Stock Exchange’s S&P/TSX composite index declined 86.14 points to 15,543.33, weighed down by losses from energy companies.

Oil prices have been on the rise in recent days after news that major producers Saudi Arabia and Russia both want to extend current oil production cuts. In January, OPEC and non-OPEC members agreed to slash production by 1.8 million barrels per day.

The efforts are meant to prop up the price of oil, which has sunk to half of its value compared to early 2014, as supply continues to outstrip global demand.

But the optimism from the possible extension was tempered Tuesday by a report from the International Energy Agency cautioning that the move by OPEC may not be enough to bring down oil stockpiles.

The June crude contract was down 19¢ at US$48.66 per barrel, while the Canadian dollar was up 0.24 of a U.S. cent at an average value of US73.55¢.

Stephen Carlin, head of equities at CIBC Asset Management, says he believes oil prices will stabilize if the cuts go ahead as planned.

“What we’re seeing too is because global growth continues to pick up, we’re seeing an improvement in global demand,” he added, noting that will also help support current prices.

Airlines were the big winner on the TSX after the federal government introduced legislation that would allow foreign investors to own up to 49% of the country’s airlines.

Shares in Air Canada finished nearly 5% higher or 80¢ to $16.95, while WestJet Airlines stock gained 2.52% or 55¢ to $22.36.

In New York, the Dow Jones industrial average pulled back 2.19 points to 20,979.75, while the S&P 500 index shed 1.65 points to 2,400.67. The Nasdaq composite index was ahead 20.20 points to finish at a new record high of 6,169.87.

Meanwhile, other commodities were mixed with the June natural gas contract down US12¢ at US$3.23 per mmBTU, the June gold contract up US$6.40 at US$1,236.40 an ounce, and the July copper contract ahead US1¢ at US$2.55 a pound.