Shares of Ciena (NYSE:CIEN) jumped 14% on Wednesday. It's easy to love the high-speed networking specialist on a day like this, but long-term investors better get used to the taste of Rolaids and Tums -- this is not a stock for weak stomachs.

CIEN Chart

CIEN data by YCharts.

Ciena shares have ended up matching the performance of the NASDAQ composite index over the last three years, but with extreme swings both high and low. The current equilibrium with the wider tech market rests on two massive jumps following the company's two latest earnings reports.

Yes, that includes Wednesday's soaring take-off. Ciena reported stellar third-quarter results in the morning, leaving analyst estimates far behind. Sales jumped 13% year over year to $538 million, while the average analyst would have settled for $534 million.

On the bottom line, adjusted earnings jumped from a $0.04 loss per share last year to profits of $0.23 per share this time. The Wall Street number? $0.16 per share. Even the most optimistic of 19 analyst firms aimed $0.01 lower than the actual result. (The non-GAAP numbers back out inconvenient expenses like share-based compensation and amortized costs of intangible assets. Put these adjustments back in, and the GAAP number remains negative.)

Ciena's earnings and cash flows have been anything but dependable lately. The company is just as likely to burn cash as it is to make some, because its core customers in the long-distance telecom industry make their infrastructure investments in a lumpy and unpredictable manner.

CIEN Free Cash Flow Chart

CIEN Free Cash Flow data by YCharts.

But that's changing right now, according to Ciena CEO Gary Smith. His company is diversifying into new markets and more customers in order to smooth out that lumpiness. "We believe that by expanding our role in the industry and extending our reach within our markets, we will be positioned to deliver higher profitability that is more sustainable over time," Smith said.

Sustainable profits would be welcome news to Ciena investors who don't enjoy the taste of antacids. Smith can back up those welcome words with some forward visibility.

Guidance for the fourth quarter exceeded analyst targets, and the order backlog "continues to grow" across domestic and international accounts. Smith didn't want to get into 2014 guidance yet, but the long-term trends do look positive: "You're going to see fluctuations. It's not always going to be a complete straight line in every dimension, but I think we're seeing very strong momentum, and I think we're well positioned for steady growth over a long period of time."

What more can Ciena investors ask for? Deliver on these statements, and the roller-coaster stock will turn into a much smoother market-beating ride.

Fool contributor Anders Bylund holds no position in any company mentioned. Check out Anders' bio and holdings or follow him on Twitter and Google+. The Motley Fool has a disclosure policy.

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