I doubt Merck is plotting a takeover before the rida results are even available and I would also tend to doubt Ariad is eager to sell when they're not so far from potential valuation inflection points. Takeover speculation is usually a waste of time.
Because for every fervid take over speculation on a biotech message board, how many pan out?
I've never made much money on a trade based on the expectation of a take over. That's an area where the pros have a big advantage in ferreting out the facts.
I really can't see a MRK munch right now with the rida results not yet publicly known, but possibly known by MRK.
Paradoxically, if rida fails in sarcoma I could see MRK trying to grab them on the cheap. MRK understands better than the market that this is just one indication of many, and MRK has a longer time horizon than the market to boot.