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 Core-Mark Holding (NASDAQ:CORE) dropped as much as 10.6% today after the company announced earnings.

So what: In the third quarter, revenue rose 4% to $2.31 billion and adjusted earnings per share fell from $1.14 a year ago to $1.01. Analysts expected revenue of $2.41 billion and earnings of $1.22 per share, so the results were well below expectations.  

Now what: Missing expectations is never good for a stock, and the drop in profit is very concerning for investors. Shares are now trading at about 17 times earnings, which is just too expensive for me given the operational momentum. If performance picks up in coming quarters I would revisit this stock, but for now it just isn't worth the price.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.