Cyan, which went public in May, is getting a lesson in the fun of being a publicly traded company. After announcing a disappointing fourth-quarter forecast Tuesday, Cyan's shares fell 13 percent in after-hours trading.

Cyan was down by 23 percent when SDxCentral happened to check less than an hour after U.S. markets closed. At press time, it had stabilized at $6.90, down 96 cents (12%).

This means the only two earnings calls Cyan has ever held have both brought the stock downward. The day after its second-quarter earnings release in August, Cyan's shares fell 18 percent to $9.08.

It's possible investors are expecting too much out of the newly public company. They might also be learning the hard way that optical-equipment revenues can be erratic (a problem Infinera has had to live with for years).

Cyan went public in May at $11 per share, closing at $11.14 on its first day.

For its third quarter, which ended Sept. 30, Cyan's revenues and losses were both better than analysts expected.

But the fourth-quarter numbers fell short. Cyan expects revenues of $30 million to $33 million, whereas analysts were expecting $46.1 million. Cyan is forecasting fourth-quarter net losses of 19 to 24 cents per share, much worse than the consensus estimate of 8 cents.

To put it another way, Cyan expects revenues to total 33 percent more than in 2013. But when you take the third-quarter results into account, the $46.1 million fourth-quarter estimate amounts to a prediction of 48 percent year-on-year growth.

In Cyan's press release Tuesday, CEO Mark Floyd's prepared statement mentioned uncertainty of the U.S. federal budget "exacerbating what would have already been a lumpy quarter, as budgets are largely exhausted towards the end of the year."

On top of that, Cyan's biggest customer, Windstream, will bring in less revenue than in prior quarters, Floyd said on Tuesday's earnings call. Cyan predicted this earlier in the year, noting that Windstream was planning to reduce capex overall in 2013.

Windstream accounted for 42 percent of Cyan's revenues in the June quarter.

Cyan does have some good signs for the future. Colt recently picked the vendor as part of a metro deployment for Carrier Ethernet services. (SDxCentral's DemoFriday is featuring the related technology in a Nov. 1 webcast.) And Cyan's gear is in the labs of four Tier 1 carriers. That doesn't guarantee any revenues, but it's encouraging considering Cyan was in none of those labs three months ago.

"I have never seen the tier 1s move as fast as they are, in looking at this SDN [software-defined networking] technology, period," Floyd said on the earnings call. "We're in conversation with multiple Tier 1s, and they're all at the same time. It usually doesn't work that way.

Cyan's Blue Planet platform also won the Best Telecom Product award at Light Reading's Leading Lights event in October. See the video evidence here.

(Analyst estimates taken from Briefing.com, which was quoting Capital IQ.)