It is possible the stock is going up due to retail sentiment and expectations of the merger going through and has nothing to do with insider trading. Simple accumulation by people like myself, without the ability to hold the stock down while accumulating.
Which means it can take off either direction hard and fast depending on the merger passing or not. Technically there is no real reason why the stock should tank if the merger doesn't pass, the company is still viable. Except perhaps for the fact that too many people are betting on it going through.