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 Oclaro (Nasdaq: OCLR) fell more than 15% in intraday trading on a sectorwide sell-off of companies whose optical (i.e., light-based) components help power telecommunications networks.

So what: The move appears to have been precipitated by less-than-optimistic fourth-quarter projections offered by Infinera's (Nasdaq: INFN) management. That stock is down more than 30% as I write this. Finisar (Nasdaq: FNSR), an Oclaro competitor, is down more than 10%.

Now what: If you're a long-term investor, you could argue that all three of these drops are buying opportunities. In Oclaro's case, the stock is priced at a discount to the 20% annual growth analysts expect the company to achieve over the next five years.

Interested in more info on Oclaro? Add it to your watchlist by clicking here.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community.

Infinera is a Motley Fool Rule Breakers recommendation. Try any of our Foolish newsletter services free for 30 days.

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.