Dendreon (NASDAQOTH:DNDNQ) shares soared on Friday, thanks to an incredibly bullish upgrade by Wall Street, with a price target essentially doubling Thursday's close. Fool health-care analyst David Williamson takes investors through the causes for Sanford Bernstein's sudden change in tone, and what it means for Dendreon.

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

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