TORONTO (Reuters) - TMX Group said on Wednesday that trading has resumed in all shares on the Toronto Stock Exchange after an unexplained glitch froze trading of companies whose symbols started with the letters M to Z.
The operator of Canada's largest stock exchange said it was still investigating the cause of the technical failure, but it ruled out hacking.
The problem, one of the worst trading glitches to hit the TMX in recent years, affected high-volume stocks such as Research In Motion and Sun Life Financial.
"TMX Group regrets this unfortunate and rare disruption to our normal market operations and the inconvenience this caused our customers," Chief Executive said Tom Kloet in a statement.
"We are continuing to investigate the root cause to ensure that the problem does not recur," he added.
The glitch did not affect all stock trading in Canada. TMX Select, TMX Group's alternative trading system, operated normally for all Toronto Stock Exchange and TSX Venture Exchange symbols. The TSX Venture Exchange also operated normally throughout the nearly two-hour long outage.
A spokeswoman for the Investment Industry Regulatory Organization of Canada, the national self-regulator for the country's investment dealers, said the stocks were also being traded normally on markets operated by TMX competitors.
An official at Alpha Group confirmed the alternative trading system continued to match trades for stocks that were frozen on the Toronto Stock Exchange.
Thomas Caldwell, an outspoken shareholder of TMX Group, played down the significance of the outage.
"Every Exchange will have breakdowns - these are computer systems. New York has had them, London has had them," he said. "We all understand that these things do happen."
The outage happened the same day Canada's competition regulator said it has "serious concerns" about a C$3.8 billion ($3.7 billion) proposal by a consortium of Canadian financial services companies to take over TMX Group, a deal that would bring most of the country's financial exchanges under one roof.
Reporting By Jeffrey Hodgson, Jennifer Kwan and Euan Rocha; editing by Peter Galloway