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 biotechnology company Halozyme Therapeutics (NASDAQ:HALO) plunged 17% today after partner ViroPharma (NASDAQ:VPHM) ended a phase 2 study combining two of their products to treat a rare genetic disease.

So what: ViroPharma is pulling the plug because patients developed antibodies against Halozyme's recombinant human enzyme rHuPH20, raising plenty of doubts over the drug delivery technology. Although the decision to scrap the study is just a precautionary measure -- the antibodies haven't been associated with any adverse side effects -- the news alone calls the long-term viability of Halozyme's platform into question.

Now what: Despite the setback, Halozye remains pretty positive about the safety of its technology.

"We have accumulated a robust data set regarding the clinical use of rHuPH20 across many different programs and indications," said Halozyme CEO Gregory Frost, "and feel confident about the safety profile of the rHuPH20 platform that has emerged from this clinical use and its continued application in our other products and programs around the world."

So while Halozyme is certainly too speculative for average investors, today's plunge might be an overreaction that biotech-savvy traders can pounce on. 


Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.