Brean Capital has come out today with a pair of substantial downgrades. First, it has downgraded VIVUS (NASDAQ:VVUS), maker of the obesity drug Qsymia, to a sell, and set the price target at a painful $7 per share. This is a 50% downside from yesterday's $14.32; the stock fell 5% as a result. Brean also downgraded Celsion (NASDAQ:CLSN) to a sell, placing the price target at an astonishing $1 per share. Celsion is also down over 5% on the news. In this video, Motley Fool health-care analyst David Williamson tells us what was behind these killer downgrades, and whether investors should be worried.

David Williamson has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.