i've always wondered how the institutions (or maybe MM's) trade stock between the US/CAN exchanges..

for instance, GNH trades on the tsx.v and the pinks. the venture exchange may do 1mil in volume, while the pinks do 10k...yet the SP spread between the two rarely becomes too great.

i'm guessing somebody somehow can buy/sell on both exchanges?

is there a certain # shares only available in the US? or can a MM borrow from one to supply another?

as always, thanks to all for the great info here.