Trading on all TMX Group exchanges, including the Toronto Stock Exchange, was shut down early on Friday following widespread technical issues.

"TMX has decided to shut down all markets for the remainder of the day. Trading will not resume today, including market on close. We apologize for the inconvenience. Further updates will be provided," TMX Group said in a tweet.

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TMX Group later released a statement saying they had identified the issue that caused the outage, but did not provide any specifics on the matter. "We have identified the issue and are working to rectify," they said. "We expect to resume trading at regular hours on Monday, April 30, 2018."

The Ontario Securities Commission, meanwhile, referred all questions regarding the outage back to the exchange.

The S&P/TSX Composite index, the main index for Canadian stocks, traded 0.2 percent higher at 15,668.93 as of 1:39 p.m. ET, which was the last update for the benchmark.

More than 177 million shares were traded on the Toronto Stock Exchange before trading was shut down, according to FactSet. The five-largest stocks traded in the Toronto Stock Exchange are the Royal Bank of Canada, Toronto-Dominion Bank, Bank of Nova Scotia, Suncor Energy and Canadian National Railway. Those stocks had traded about half their 30-day average volume by the time trading was shut down.

The exchange's normal trading hours are 9:30 a.m. to 4 p.m. ET, same as the New York Stock Exchange and Nasdaq Exchange. Trading continued on other exchanges throughout Canada, including Nasdaq's exchanges.