TORONTO - Stock traders gnashed their teeth and stared in disbelief at blank ticker boards Wednesday as Canada's main stock markets took the day off sick, losing an entire session of trading after being paralyzed by data transmission problems.

It was the first time the Toronto Stock Exchange has been shut down for a whole day due to a technical glitch and Bay Street greeted the development -- particularly unwelcome after months of trading turmoil -- with consternation.

"This is ridiculous, this nonsense with this system -- I don't know what to think," said Fred Ketchen, manager of equity trading at Scotia Capital.

"I don't know if a mouse crawled in and bit through a piece of cord or what the Sam Hill happened. But obviously, it's a data disruption and it leaves you all standing around picking your seat."

TMX Group (TSX:X), the company that operates the TSX and the junior TSX Venture Exchange, blamed the day-long halt on "technical issues with data feeds" and not its main Quantum trading engine.

Just after trading opened, TMX halted both trading platforms, saying it wanted to be fair to all participants by ensuring they all received the same data.

However, the exact cause of the problem wasn't made clear.

"We have a high level of confidence that we have fixed the problem," deputy CEO Luc Bertrand said in an interview late Wednesday, noting that the market should resume trading on Thursday.

"Everybody has to appreciate that this is technology and nobody can give you a 100 per cent, iron-clad guarantee when you're dealing with such complex systems."

Bertrand said a transmission problem prevented some clients from receiving data, but he declined to offer any more details. The market was then halted out of "concern of maintaining fairness and transparency and proper dissemination of data to all participants."

It wasn't immediately clear what logistical fallout would follow, and some analysts suggested that TSX representatives could've done a better job of informing the public.

"It contributed to confusion and it contributed to a lack of credibility," said John Stephenson, portfolio manager at First Asset Funds Inc. said of the company's intermittent three-sentence press releases.

The problem, the third major glitch this year at the TSX, began early in the session, when the market appeared to have failed to open at the regular time of 9:30 a.m. ET.

TMX Group tried to clean up some of the mess by putting markets into a pre-open state between 3 p.m. and 5 p.m. ET to allow traders the option to cancel, add or change orders they'd placed in the system.

From a competitive standpoint, the glitches couldn't come at a worse time for the TMX Group, as it faces a rash of new alternative trading systems that are hoping to lure away customers.

These off-market electronic platforms have had little impact so far on the business of the TMX, but a weighty new competitor started up Nov. 7 with the launch of Alpha Trading Systems.

Paul Thornton, president and portfolio manager at Global Maximum Power, noted that there were already a lot of reasons not to invest in stocks "and when the exchange cannot open and give you a quote, that is just another one."

Many shares of big Canadian companies are also traded on the New York Stock Exchange, including such market heavyweights as Research In Motion Ltd. (TSX:RIM), Royal Bank (TSX:RY) and energy giant EnCana Corp. (TSX:ECA).

Ketchen said that it's possible for some investors to trade through New York -- but it takes extra time.

"If you know what you're doing, you should be able to do it in a couple of minutes," he said.

"But if you have a huge long list of things you have to do, obviously the time will lengthen out. You have to pull it out of one market, key this thing through into another market and have it go."

The outage is the latest in a string of problems that have hampered trading for Canadian investors on the TSX.

On Oct. 10, trading was halted on 38 stocks for more than two and a half hours because of a technical problem. Jovian Capital Corp.'s Horizons BetaPro exchange traded funds weren't able to trade at the open on Oct. 14.

And on Nov. 7, trading on the TSX didn't start until nearly 10 minutes after the scheduled opening time. The TSX said that problem originated at services provided by Standard and Poors in New York.