Is Teva (NYSE:TEVA) genuinely concerned about Biogen's  (NASDAQ:BIIB) BG-12's safety, or is it more concerned about the oral MS drug's impact to its own Copaxone sales? Motley Fool health-care analyst David Williamson dives into the surprise plea to the FDA and what it means for investors.

David Williamson has no position in any stocks mentioned. Follow him on Twitter @MotleyDavid.

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