With the release of ASCO abstracts, essentially a huge clinical trial data release ahead of the annual cancer conference, we witnessed a few pops and drops among biotech stocks. 

In this video, healthcare analyst David Williamson takes a closer look at two stocks seeing 20% moves -- Oncothyreon (NASDAQ:ONTY.DL) and Halozyme (NASDAQ:HALO) -- and discusses what these events mean for investors.