If someone has been in fact accumulating
You would assume that they are likely accumulating for a hostile bid. If the entity was getting close to the desired position and the stock started to break out then you'd see panic buying from the entity to keep their average as low as possible as they complete their position. CIBC stood out MASSIVELY compared to any other house position. Almost all the other big names were actually on the sell side by the end of trading on Friday. CIBC was on the buy side by about 32 million dollars (if I remember correctly) and was miles ahead of anyone else on the buy side. Could it just be a massive covering of a short position? CIBC and Anon usually dominate the trading space on this stock so I wouldn't be too surprised.