I did find an acticle on S.Watch about these other trading platforms, part of which is below:

Pure in third, Alpha grabs a little more from the TSX

2011-03-15 20:44 ET - Street Wire

by Stockwatch Business Reporter

Pure Trading was the third most active Canadian alternative trading system for the week ended March 11, 2011. Alpha Trading Systems took first place, trading 274 million shares a day for 21.5 per cent of total Canadian volume. Chi-X Canada took second place, trading 54.9 million shares a day for 4.3 per cent; Pure took third place, trading 43.1 million shares for 3.3 per cent; and Omega ATS took last place, trading 22.1 million shares for 1.7 per cent. Together, the ATSs handled 30.9 per cent of Canadian volume, while the Toronto Stock Exchange and the TSX Venture Exchange handled 69.1 per cent.

Of securities listed on the Toronto Stock Exchange, Alpha captured a record 31.3 per cent of trading volume, while Chi-X took 5.6 per cent and Pure handled 4.4 per cent....

I am a new user so hope this did not get me in trouble.

But it makes me wonder what information on trades I, we, are missing, since alpha captured 31.3 per cent of the trading volume on the tsx??