December saw shares of Rigel Pharmaceuticals (RIGL 2.50%) drop more than 20%. The tumble happened after Rigel's partner AstraZeneca (AZN +0.59%) released phase 2b data concerning their experimental rheumatoid arthritis drug fostamatinib. While the drug outperformed the placebo, it failed to beat AbbVie's (ABBV +0.31%) Humira. (AbbVie, formerly the branded pharmaceutical division of health care powerhouse Abbott Labs (ABT 1.86%), is now listed on the NYSE). In this video, Motley Fool health care analysts Max Macaluso and Brenton Flynn break down this story for investors.
