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 oilfield service company RPC (NYSE:RES) lost 12% of their value today after the company reported earnings.

So what: Revenue dropped 15% in the first quarter to $425.8 million, well below the $470.1 million estimate. Net income dropped 57% to $35.1 million, or $0.16 per share, and analysts expected a $0.25-per-share profit.  

Now what: Management pointed to strong competition as the reason revenue and earnings have fallen over the past year. Long-term contracts are also expiring, forcing the company to compete in the spot market. The oilfield service business is under a lot of pressure right now and I'd simply stay away from this volatile space.

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Fool contributor Travis Hoium and The Motley Fool have no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.