I'm uneasy about this; maybe someone can check my bullcrap here.
The upside is say 13.3% from here. If the downside is 40% and the chance of the deal closing is 75% then it's barely break-even before the time value of money. With the time value of money at 5%, breakeven is about 85% chance of the deal closing.
I have no idea how to estimate the probability of closing, and proving to myself that it's way over 85% seems impossible.
If Wyeth is really worth what it costs or something, so that the downside is zeroish, then maybe the deal is worthwhile. I guess I should take a look at that.