Tom Bradley at Steadyhand reports that the Alpha Group (owned largely by Canada's big banks) is being investigated for conflicts of interest by the Investment Industry Regulatory Organization of Canada (IIROC). The concern is that your trades may not be executed at the best possible price.
The Alpha Group seek to divert trades from the TMX to the Alpha exchange. Their initiative aims at "establishing a market place driven by profit and the best interest of the industry." Of course, profits come out of traders' pockets.
I try to be wary any time I make trades, which isn’t very often. I check the bid-ask spread to make sure it isn't too wide, and I check that my trade is executed close to the appropriate price. Most of the time I get the advertised bid or ask price, but occasionally I get a slightly better or worse price. However, I don't trade often enough to judge whether anything unusual is going on.
I would think that any extra profit by an exchange would come from either wider spreads or failure to execute trades at the advertised bid and ask prices. But who knows – businesses seeking higher profits can be very clever.
The incentive to try to extract a few extra cents from each share traded is powerful. We need a strong IIROC to prevent systemic abuses. As an individual, one of the best forms of protection is to trade less often.