Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of the Vitamin Shoppe (NYSE:VSI) were looking under the weather today, falling as much as 10% after a disappointing earnings report.

So what: The health-supplement chain actually beat earnings estimates by $0.03 with a per-share profit of $0.72 as revenue grew 12.5% to $279.1 million, slightly below expectations. Comparable sales were up 4.5% in the quarter. The retail chain also added 44 stores in the period, 31 via acquisition, bringing the total count to 621. Investors, however, seemed to be disappointed with the revenue miss and same-store sales expectations of low-to-mid-single digits for the year.

Now what: This was the second quarter in a row in which Vitamin Shoppe shares tumbled on its earnings report as the market seems to be saying that the stock is overvalued. Shares had climbed as high as $65 earlier in the year, but now they seem to be fairly valued at a price almost a third down from its peak. I would have avoided Vitamin Shoppe before but with an aggressive store expansion plan, and a modest same-store sales increase expected, shares look reasonably priced today.

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Fool contributor Jeremy Bowman has no position in any stocks mentioned, and neither does The Motley Fool. 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.