when the canadian dollar is low trade like .75 us...

the nyse cnq will move 1.25 more than the tse cnq... i think this is what your looking at.. its just the currency...

if its out of line to the us:can ratio... it get arb into line by simutaneous no risk trades.. by the brokerage houses..

this will knock it back inline... i often convert my currency by buy and selling tse to nyse and vis versa.. sure beats spread trading of the currencies.

but unless your into the 10 of millions its hard to do a quick flip back unless you see lower nyse higher tse to the ratio.. its no risk ..