I've got a theoryNG is up, and heading much higher, oil's up and heading higher. CR is down. But the number of individual shareholders (as compared to institutions) is so small that the banks can (I'm sure) see all of the individual retail positions, including margin.
So they know how hard they have to squeeze to force margin calls, and since institutions won't liquidate on transient swings, the banks can push stocks on trend way past points that reason would dictate (in the short-term) to force retail (and particularly) margined holders to liquidate.
If you think of the average volume, I'm guessing there are maybe 10000 individual holders of companies like Crew in the Canadian market. That's a trivial number of positions for a bank to track. This would explain a lot of the apparently inexplicable behavior in Canadian exchanges.