I've owned stocks in several others that went through this same process of alleged wrongdoing.
STEC and ACAS come to mind.
What happens is that the court appoints one law firm to represent investors if they decide to proceed with a legal claim on behalf of all registered investors during the time frame from announcement to deal closing.
In this case it is possible to work out a pre court deal with tsrx and cubist.
In my past experience I had received quite a pile of papers to read and sign and only received a small percentage as a settlement. Something was better than nothing though. O,and I should mention that this took several years before I heard anything from the court. So print any record of your ownership and how many shares owned during the time frame in question.
It may seem that nothing is being done, as I was surprised in my own case.
Not merger related.
As best I can remember it was over misrepresentations prior to earnings release in the case of Stec.
The acas was somewhat similar but some years back.
Maybe Google it if you're curious.
They definitely were not merger related so there may be some legal difference in how it is handled in the case of tsrx.