I see your point about those Achn VCs sells. However it is my opinion it does not say anything about the probability of a future BO event from their point of view.
I would do exactly the same (ie lighten up the load) if I were in their position. It would be reckless and foolish otherwise.
These "biotech values" are not exactly buy and hold situations :) lol.
Maybe ... but MRK did in-house testing of 21437 to assure themselves before they agreed to the buyout.
Hedge funds like RA or QVT which sold part of their holdings have investors they need to be cognizant of ... BTW, RA is still the largest shareholder with 13 MM shares and 3 MM call options at $5 ...