My guess is that some of the institutional shareholders are getting out. Trading volume picked up significantly in March -- they were probably trying to unwind their positions by EOQ. If you look at the institutional holders, they are relatively large. Orbimed, for example, manages over $7B. Their holdings as of 12/31/12 valued at today's price is about $9M. This is a rounding error for them. Perhaps they or one or more of the other institutions are just taking their losses and moving on. Clear sign of no-confidence in this company.