Threadkiller, you seem to be suffering from the misconception that prices of stocks are linked to the underlying fundamentals of the company. While that may seem like a reasonable idea, it just isn’t so. And before you venture into the world of wall street trading I highly recommend that you get past this line of thinking.
Stock prices instead are based on what traders think other traders will pay for the stock in the near future. Typically, when a company buys another company and then lays off a bunch of workers, that stock will bounce. I’ll leave it to others to argue if this makes business sense or not, but to me it doesn’t matter. This is what is routine and so this is what happens.