the only support for this statement is what I've witnessed (and posted here occasionally) with my own eyes.
You can also go back and review the daily charts...you'll notice a handful of intra-day spikes (both up and down), normally with less than 100 shares. Within a day or two of each occurrence the pps normally heads in the direction of the spike.
don't have a reason why, nor do I think I really care...it could all just be a coincidence. It could also be a result of the cross-listing and all shares going through the Canadian exchange...however the spikes are usually much more than the difference in exchange rates.