Actually I don't believe they plan to price or sell any shares now. It's just a shelf filing, giving them the opportunity in the future. Arguably, if they know upcoming catalysts are about to drive the share price higher (perhaps Galaxy-1 OS), you'd want to be prepared to take advantage of and raise capital against that premium. I believe Pharmacyclics did something similar after Phase 2 of Ibrutinib.
I suspect what happened is that we had a sequence of stop losses get tripped. Just love it when the computers take over. Interesting to watch but not concerning. After all Dr. Ramachandra didn't leave his well paid senior VP and Chief Science Officer position at Hospira without first getting an inside peek at Synta. That alone speaks volumes.