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 PharMerica (NYSE:PMC) rose nearly 25% today after the company released an all-around superb earnings report for the third quarter.

So what: PharMerica's revenue came in at $436.8 million for the quarter, a 1% year-over-year decline but much better than the $401.7 million consensus. The company's adjusted earnings of $0.49 per share also trounced Wall Street's projections of $0.33 in EPS. Guidance for the full year now comes in ahead of what Wall Street had expected on the top and bottom lines -- revenue of $1.7 billion to $1.725 billion bests the $1.67 consensus, and full-year EPS guidance in the $1.71 to $1.76 range runs roughshod over the $1.55 bottom-line consensus. Both ranges were significant upgrades from earlier guidance ranges, and point to renewed strength for the pharmacy-services company.

Now what: Today's pop returns the up-and-down shares of PharMerica to 52-week highs, and today's post-pop price is actually higher than any level seen since the summer of 2010. But this yo-yo performance is worth considering before you dive in, as PharMerica's trailing 12-month revenue was already at the high end of its guidance range before today's earnings release. This pop was a great reward for loyal shareholders, but newly interested investors may want to tread cautiously.

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