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 do-it-all renter United Rentals (NYSE: URI) fell 12% today after the company posted disappointing earnings.

So what: Revenue was up 9% to $523 million but still fell below analysts' expectations of $551 million. The net loss of $20 million, or $0.34 per share, is more worrisome because investors were only expecting a $0.12 loss.

Now what: Construction activity isn’t picking up as quickly as analysts had expected and United Rentals paid the price this quarter. Management sounded confident going forward and is still expecting to increase rates 5% this year. If this were a disappointing profit instead of a disappointing loss I might look for a silver lining, but I would like to see United Rentals move into the black before jumping into shares.

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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. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.