Why Exelixis, Inc. Slumped Today

Exelixis (NASDAQ: EXEL) is down 12.3% at 2:18 p.m. EDT after an analyst at Leerink Partners downgraded the biotech to market perform. Management also sold some shares, which could be contributing to the downward direction of the share price.

Exelixis is up 65% this year, even after today's sell-off, and it's up over 1,300% over the last three years; it's understandable if analysts and investors are wondering how much further the biotech can run. Of course, being called overvalued is one of the six signs of a Rule Breaker, so the worry isn't necessarily justified.

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Source: Fool.com