Actually, there may be a bit of a special case with BMO. It seems to me that when registering BMO HELOCs there is a unique little bit of language that BMO uses to define the Prime rate as something other than the norm. They define their HELOC prime rate separate from the bank's prime rate. My guess is that they are using that to adjust the HELOC rate independent of the prime rate. To my knowledge, t hey are the only bank that has language in their agreement allowing them to do so.
While the earlier poster (whatever his name is
) is correct in saying that these loans are made 'on demand', the fact is that most banks wouldn't want to risk the business by actually calling the loan and then offering a new one at a higher rate. BMO's version allows them to avoid such unpleasantness by simply changing the HEOC Prime rate.
I can't speak to Manulife's version as I only did a couple of dozen of those and haven't seen any since last summer. I don't recall there being unusual language in the Manulife One documents, but I coul be mistaken.