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 Tutor Perini (NYSE: TPC) fell as much as 13.6% in early trading before closing down 9.4% on a second-quarter earnings miss and lower 2011 guidance.

So what: Revenue fell 10% to $819.9 million while profit fell to $0.41 a share from $0.66 in last year’s Q2. Analysts had been banking $0.43 on just $801.9 million in revenue, according to data compiled by Yahoo! Finance.

Now what: Worst of all, management lowered full-year guidance to $3.6 billion to $3.9 billion in revenue, down from earlier estimates of $4.2 billion to $4.7 billion, Reuters reported. There just isn't enough interest in the company's civil-engineering services right now. But ask Fools and they'll tell you the downdraft won't last. More than 600 rating the stock in Motley Fool CAPS give it five out of five stars. Do you agree? Would you buy at these levels? Weigh in using the comments box below.

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