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 Express Scripts (Nasdaq: ESRX) have popped today by as much as 15% after the company reported third-quarter earnings ahead of analysts' expectations.

So what: The pharmacy benefits manager reported third-quarter revenue of $11.6 billion, which translated into adjusted earnings per share of $0.79. Analysts were calling for $11.3 billion in revenue and $0.77 in earnings per share.

Now what: The company has been trying to merge with MedcoHealth Solutions (NYSE: MHS) recently in a $29.1 billion deal, and the CEOs of both companies have expressed confidence that the acquisition will pass regulatory muster. Express Scripts has also been locked in a contract dispute with drugstore company Walgreen (NYSE: WAG), which has been weighing on shares. Analysts largely think the dispute with Walgreen won't see a resolution until next year.

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