The operator of the Toronto Stock Exchange and the Montreal Exchange said the issue that forced an early end to trading Friday was the result of a "hardware failure."
TMX Group said in a statement Saturday evening the hardware failure occurred in the central storage appliance of the trading system.
TMX also confirmed the issue wasn't caused by a cybersecurity attack.
The failure on Friday afternoon halted all trading in stocks, options and derivatives on TMX's markets. Also affected were the TSX Venture Exchange, a market for small capitalization stocks, and the TSX Alpha Exchange, a market geared to active traders.
The problem began affecting the Montreal Exchange at 1:37 p.m. ET, and began hitting the TSX less than two minutes later. TMX Group sent out an initial tweet warning of the problem shortly after 2 p.m.
Remediation efforts started Friday afternoon and the defective device was replaced and tested, TMX Group said.
Because of the timing of the failure Friday, TMX Group stated there wasn't time to ensure an orderly market re-open and closing that day.
All systems will be ready for the start of business as usual on Monday.
"TMX is committed to applying the lessons learned from this incident to help us prevent such issues from recurring in the future," TMX Group CEO Lou Eccleston said.