Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Synta Pharmaceuticals (NASDAQ:SNTA.DL) sank 16% today after Stifel downgraded the biotechnology company from hold to sell.

So what: Synta surged yesterday after announcing positive news for its lead cancer drug, ganetespib, but today's downgrade by Stifel's Brian Klein is forcing Mr. Market to sober up quickly. So, while investors were quite excited about the fact that ganetespib had been chosen for an investigator-sponsored trial, Klein's call suggests that Synta's fundamentals remain largely unchanged. 

Now what: According to Stifel, Synta's risk/reward trade-off is rather unattractive at this point. "SNTA reported 4Q13 LPS of $(0.31), in line with our $(0.32) estimate," noted Klein. "Due to further delayed data readouts, changes in clinical trial designs, leadership changes, and the further need for capital, we are downgrading Synta (SNTA) to a Sell." Given Synta's worrisome cash-burn rate and still highly speculative pipeline, it's tough to disagree with Stifel's cautious stance.