MS, the way I understand it, and it has been the case in the past, albeit with several US companies, is that the shareholders receive compensation for their shares based on the takeover deal, and so do warrant holders. There is, I belive, a recognized method for determining the value of the warrants at the time of the deal, and that's what warrant holders receive. The warrant can always be exercised after announcement and before closing of the merger.

So, I do not believe exercise of warrants is much evidence at all that POET is being acquired. In fact, I would say canceling BNN is more evidence of that than exercise of warrants, although FJ has earlier made a good point about wanting the voting power associated with shares rather than holding non-voting securities like warrants.