In this video, health-care analyst David Williamson walks investors through Sanofi's (SNY 1.47%) rough quarter, and explains why investors need to keep an eye on the bigger picture. Sanofi is dealing with the loss of patent protection on blockbuster Plavix, but investors have a lot to be excited about, especially the potential of diabetes drug Lantus, and also multiple sclerosis drug Aubagio (although it faces steep competition from Biogen). Watch and find out if Sanofi is a stock that should be on your radar.