Petaluma networking technology developer Cyan reported revenues fell 30 percent in the fourth quarter following a decline in sales to its largest customer.

The company reported $20.9 million in revenues for the quarter ending Dec. 31, down from $29.8 million a year ago.

Losses grew to $11.5 million, or 25 cents per share, during the quarter, up from a loss of $3.5 million, or $1.37 per share, for the same period last year. The non-GAAP earnings exclude stock-based compensation costs which the company believes are not indicative of its core operating results.

Cyan warned investors Jan. 6 that its largest customer had unexpectedly reduced its purchases. Despite the fourth-quarter drop in sales, Cyan still boosted annual revenues to $116.6 million, up from $95.9 million in 2012.

"Overall, 2013 was a very important year for Cyan as our packet-optical technology and SDN software was deployed as part of customer network transformation efforts around the globe," Cyan chairman and CEO Mark Floyd said in a statement.