TORONTO -- North American stock markets enjoyed a relief rally in the aftermath of interest rate cuts on both sides of the border and a strong primary night for former U.S. vice president Joe Biden.

The Bank of Canada cut interest rates by 50 basis points Wednesday, a day after the U.S. Federal Reserve made a surprise emergency cut of equal size. Investors welcomed the reductions but also wondered if they signalled that central banks had evidence that the impact of the COVID-19 virus was worse than previously thought.

Those concerns appeared to dissipate Wednesday as investors accepted that the interventions meant the banks would support the economy so it doesn't fall on its face, says Allan Small, senior investment adviser at HollisWealth.

"Today people are kind of turning around and saying it seems like intervention is global," he said in an interview, noting that Japan has also said it will do what is required.

"I think there's this idea that the central banks even though they can't produce a cure for the disease they will do whatever it takes to help the economy during this time when obviously there's going to be a slowdown pretty much in most sectors."

The U.S. House of Representatives passed an US$8.3 billion emergency spending bill to battle the coronavirus outbreak that exceeds President Donald Trump's US$2.5 billion plan.

Biden's strong showing in a series of Democratic presidential primaries known as Super Tuesday also brought relief, especially among health care companies that fear rival Sen. Bernie Sanders medicare-for-all proposal.

And the U.S. 10-year treasury yield inched above one per cent a day after dropping to a record low.

"I think that spooked the market. Today they seem more stable. I think that has helped," said Small who referred to the various measures as enducing the relief rally.

The S&P/TSX composite index closed up 355.91 points or 2.2 per cent at 16,779.53 for the largest single-day gain in 14 months.

In New York, the Dow Jones industrial average was up 1,173.45 points or 4.5 per cent at 27,090.86. The S&P 500 index was up 126.75 points at 3,130.12, while the Nasdaq composite was up 334.00 points at 9,018.09.

The Canadian dollar traded for 74.67 cents US compared with an average of 74.83 cents US on Tuesday in the wake of a decision by the Bank of Canada to cut its key interest rate to address worries about the economic impact of the new coronavirus.

All 11 major sectors on the TSX gained led by technology, real estate and health care.

Shopify Inc. and Lightspeed POS Inc. gained 7.7 and 7.5 per cent, respectively.

Cannabis producers Cronos Group, The Green Organic Dutchman Holdings Inc. and Hexo Corp. saw their shares gain as much as 12 per cent.

Materials moved higher as Teck Resources Ltd. gained nearly nine per cent as copper rose.

The April gold contract was down US$1.40 at US$1,643.00 an ounce and the May copper contract was up 1.3 cents at US$2.59 a pound.

Energy moved higher despite a dip in crude oil prices as Russia signalled it's opposed to Saudi Arabia's push for drastic oil cuts to address demand shortfalls.

The April crude contract was down 40 cents at US$46.78 per barrel and the April natural gas contract was up 2.7 cents at US$1.83 per mmBTU.

The Bank of Canada's rate cut coupled with the federal government's recent easing of its stress test for residential mortgages risk re-igniting the housing market in large urban cities and raising the chances of a housing bubble, said Small.

"It's like you're adding kerosene for the fire," he said.

"One day rates will be higher and how will people afford it? I don't know but one day hasn't come in a long time."