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 Teradyne (NASDAQ:TER), which bottomed out at a 10% loss before lunchtime, have clawed their way back to a slightly less gobsmacking 4% loss as of this writing. Despite a strong earnings report, Teradyne failed to wow investors with its forward guidance. The interplay between tomorrow's weakness and today's apparent strength is a major reason for the yo-yo performance today.

So what: Teradyne reported revenue of $428.9 million, well ahead of Wall Street's expectation of $407.4 million, despite suffering a 22% year-over-year decline. Earnings of $0.43 per share also trounced the $0.32 consensus. However, Teradyne now views its third quarter in a rather disappointing way; the company estimates between $425 million and $465 million in revenue and $0.39 to $0.49 in EPS. Both numbers are far below the analyst consensus, which sought $523.5 million on the top line and $0.60 in EPS.

Now what: Teradyne has had a difficult time growing its revenue and earnings since roaring back from the financial crisis. The company's free cash flow has also been in a slow multiyear decline. Guidance doesn't offer investors the promise of growth they had been hoping for, but shares are trading rather modestly, with a 20 P/E at the moment. Growth is important -- without it you're only buying a value trap -- and today's report didn't provide quite the momentum Teradyne investors were looking for. This would be a good time to do some more digging to determine whether this company can deliver the gains you need.

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Fool contributor Alex Planes has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. 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.