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 Motley Fool Rule Breakers pick Infinera (Nasdaq: INFN), an optical networking specialist, fell more than 30% in intraday trading after the company predicted weak fourth-quarter results.

So what: In a conference call following the earnings report, Infinera Chief Financial Officer Ita Brennan warned that Level 3 Communications (Nasdaq: LVLT) wouldn't contribute as much to Q4 revenue as it did in Q3, when it accounted for 19% of sales. Global Crossing (Nasdaq: GLBC) was the only other customer to account for at least 10% of revenue. Brennan also cited a lack of visibility into the timing of deals in waxing cautious about Infinera's fourth-quarter outlook.

Now what: It's tough to blame investors for selling when they've waited long, painful years for Infinera to pay off. Now, Brennan is asking them to be just a little more patient. I can see the argument: Big deals are hard to time and even harder to predict. I'd wait for further clarity on the health of the sales pipeline before buying more or opening a new position.

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Fool contributor Tim Beyers is a member of the Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. You can also get his insights delivered directly to your RSS reader. The Motley Fool owns shares of Infinera and is also on Twitter as @TheMotleyFool. Its disclosure policy is at least 10% better than other disclosure policies.