In the biotech space today, three stocks made absolutely massive moves, with each popping or dropping by more than 20% in a single day. First up is Peregrine (NASDAQ: PPHM), the day's biggest winner by far, up nearly 50% today on the announcement that it would be announcing results for its preclinical immuno-oncology drugs at an upcoming conference next week. Motley Fool health-care analyst David Williamson notes here that despite the remarkably strong interest in this space, this feels as if the market is overbuying the rumor. With the company's phase 3 drug Bavituximab having had some troubles with its phase 2 testing, this is a stock he recommends staying away from for the moment.

Today's other winner, Arrowhead Research Corp. (NASDAQ:ARWR), saw shares soar upward 25% after two Wall Street analysts showed the small-cap company some love. Deutsche Bank initiated coverage on the stock with a "buy" rating and a $45 price target. RBC also initiated coverage with a buy and a $35 price target but saw its bull case to be potentially over $60. The market is excited over the company's hepatitis B drug. David discusses what to watch with this company, and why he'll be keeping a close eye on this one.

And finally, Xoma (NASDAQ:XOMA) is today's big loser, down 25% after pausing the development of its osteoarthritis drug Gevokizumab. While this isn't completely the end for Gevokizumab, this was a very big indication for the drug. However, since the drug is being tested in a whopping 11 indications, losing just one probably doesn't warrant having the company lose a fourth of its value.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.