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 medical clinic billings and records software specialist athenahealth (Nasdaq: ATHN) surged 14% today after its quarterly results and full-year profit outlook topped Wall Street expectations.

So what: Thanks in large part to strong physician additions, athenahealth posted second-quarter adjusted earnings of $0.22 per share, versus the average analyst estimate of $0.19 per share. The shares are touching new 52-week highs on the market-beating report, so it's clear that investors fully expect athenahealth's positive sales trend -- particularly from its business services segment -- to continue.

Now what: I'd be cautious about riding this recent wave of momentum. Given today's double-digit rally, the shares are now up 150% over the past year and trade at a rather unsettling forward P/E of 51. With main rivals Allscripts Healthcare (Nasdaq: MDRX) and McKesson (NYSE: MCK) available at far cheaper prices, athena doesn't seem like the healthiest bet at this point.  

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