Canada's biggest bank-owned investment dealers are spearheading plans for a new stock trading system that will rival the Toronto Stock Exchange.

Following that announcement, shares of TSX Group slid almost 12 per cent, falling $5.67 to finish at $41.77.

The group of dealers involves in the new market includes BMO Capital Markets, Canaccord Capital Corporation, CIBC World Markets, National Bank Financial, RBC Capital Markets, Scotia Capital Inc. and TD Securities Inc.

In a release issued prior to the opening of equity markets Thursday, the group said their new trading system would be open to all dealer institutions that want to join as participating organizations.

The dealers said their alternative trading system, dubbed Alpha, is expected to launch in 2008, subject to receiving the required regulatory approvals.

"Global capital markets are changing," said Jos Schmitt, the CEO of the new trading system.

"The future strength of Canadian capital markets depends on our ability to achieve the same kind of efficiencies already being realized around the world by leveraging today's technology.

"This new Canadian-driven trading platform is being designed to find those efficiencies, increasing both competitiveness and liquidity," Schmitt said in a release.

Alpha would be the latest alternative trading system to compete against the TSX Group. Last year, Instinet and Pure Trading both announced plans to start alternative trading systems of their own to cater to the growing institutional market for fast, program-based trades.