What rumour? I think 2B would be a fair take-out before the 2014 data release. Discount for pre-results, but good value for the relative risk. Might be too low for some, but I'd take it without having to feel like suing someone.
One could easily assume that back in 2011, when the rumor about Goldman shopping the company was floating around, some big pharma looked at the bone scans and the RDT results and floated an offer in the $2B ballpark (the valuation was above $1.5B at the time). If the BOD scoffed at $2B back then....they definitely aren't going to jump on it now with Cometriq FDA approved and 4 Phase 3 trials reading out months from now. Heck GDC 0973 was barely on the radar in the summer of 2011.
If we are going to speculate on buyouts, I'm going to say anything lower than $3B is a non starter. And for that too happen, the current valuation needs to get closer. We'll see, but if all the key players (a big pharma who wants EXEL, the institutions who have huge positions, and the BOD) plays ball, we'll just keep moving up until everything is in position. The data trumps everything, but IMO if big pharma waits on a proposed buyout until after the key Comet data is released, it changes everything.
If Comet reads out positive, the chances of someone scooping up EXEL for less than $3B is lowered exponentially. Let's face it, positive Comet readout equals a $5B valuation at worst. If you don't believe that, look at MDVN. They only have 50% of Xtandi.