The last day of November saw the Dow Jones Industrial Average (INDEX: ^DJI) launch 490 points higher, its best gain since 2009, as central banks teamed up to ease euro-crisis fears. For the month, the DJIA closed up slightly; however, several well-known health care companies fared significantly worse.

Companies with market caps under $150 million were screened out, as low valuations leave shares susceptible to bigger price swings. For instance, November's biggest plunge went to Alimera Sciences (Nasdaq: ALIM), which suffered a 79% collapse when the FDA rejected the company's flagship drug candidate, Iluvien, leaving the stock down 82.1% for the month.

Here are the five worst-performing health-care stocks in November. What you are about to see isn't pretty; parental discretion is advised.


% Change in Share Price

Vertex Pharmaceuticals (Nasdaq: VRTX)  (23.3)
Seattle Genetics (Nasdaq: SGEN)  (23.5)
Human Genome Sciences (Nasdaq: HGSI)  (25.2)
Dendreon (Nasdaq: DNDN)  (18.8)
MAKO Surgical (Nasdaq: MAKO)  (21.5)

Source: S&P Capital IQ.

Investors are concerned that the increasing competition in hepatitis C treatments will leave Vertex's Incivek as a short-lived best-in-class treatment. Both Human Genome Sciences and Dendreon have struggled after disappointing launches for their respective drugs, Benlysta and Provenge. Seattle Genetics' tough month happened even after one analyst opened coverage on the company with a buy and a $20 price target, while another raised Seattle Genetics' Adcetris sales estimates. MAKO Surgical missed analyst earnings estimates by a penny and have trended down since.

But just because these five companies had a rough go of it in November, that doesn't mean the bad times will continue. Track tracking them using our free watchlist service, My Watchlist.

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David Williamson owns shares of Dendreon, but he holds no other position in any company mentioned. Check out his holdings and a short bio. The Motley Fool owns shares of Dendreon. Motley Fool newsletter services have recommended buying shares of MAKO Surgical and Vertex Pharmaceuticals. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.