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 Laboratories (NYSE: CLB) fell 17% today after the company reduced third-quarter earnings guidance.

So what: Management now expects third-quarter revenue to be between $240 million an $245 million and earnings per share of $1.09 to $1.13. The reduction is due to a decline in U.S. and Canadian on land rig counts.

Now what: Management had assumed a flat rig count in its previous projections, so it's no surprise that expectations are down. The reduction in revenue guidance was only $10 million in the bottom end and $0.08 per share, so I don't think this is the end of the world. I'm not a buyer on the dip today, but if shares continue to slide another 10% or so, the current 23 P/E ratio will begin to look better -- and when drilling picks up again, so will the stock.

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Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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