Sell-ff just looks technical, a lot of biotech is selling off today, check out XBI. Biotech has been the leading group in 2013, and we're seeing some rotation. If you wish to protect some profits it may not be a terrible idea, but keep some skin in and re-load after this selling stops.
The sector that appears to be working is old tech and industrials at the moment, all healthy for a sustained bull market IMO.
We are long time into the territory manipulation by Mr. Market. I will guess these events awaits us 1) approval of CLL in one month IMO. 2) start of RA phase 1 in 3 months IMO. 3) good trial result of MLL leading to approval. We might have some results from other trials but they are not that forceful as above 3. I will stay my position until the fulfillment of above 3.
If Imbruvica became a treatment for MM it would be as large or larger than the current prospect for MCL treatment. If it became first line treatment for CLL that would be the big one especially in younger population. I am only spouting some of what I have read so if I am wrong then I misinterpreted.