This year, investors had become accustomed to a "one-way" market; through May 17, the S&P 500 (^GSPC 0.36%) was up a very respectable 14% year to date, and the Dow Jones Industrial Average (^DJI 0.71%) performed even better, with a gain of 14.5%. Since then, consistently rising stock prices have been replaced with a more volatile environment. A greater frequency of losing days has emboldened market bears, who think the rally we've witnessed can only be followed by a nasty comeuppance. Are stocks overvalued and destined for a fall? In the following video, Motley Fool contributor Alex Dumortier explains why one bearish argument simply doesn't add up.
