Ixia shares fell Friday, a day after the maker of network hardware reported larger losses in its fourth quarter and full year. New revenue from recent acquisitions wasn’t enough to offset a large tax-related write-down in the quarter.

The Calabasas company reported late Thursday a net loss of $31.3 million (-50 cents per share), compared with a loss of $18.3 million (-29 cents) a year earlier.

Revenue rose 37 percent to $56.1 million. Ixia bought a data network testing product line from Agilent Technologies in October that added $6.9 million in new revenue, with another $6.9 million coming from clients gained from Catapult Communications, which it acquired in June.

Chief Executive Atul Bhatnagar noted that core revenues also increased by 9 percent sequentially.

“2009 was a pivotal year for Ixia, and the fourth quarter offered strong evidence of the success of our strategy,” Bhatnagar said in a press release. “Demand was broad-based on both a product line and geographic basis and we are cautiously optimistic that this demand will continue into 2010.”

Excluding one-time items, including a $27.6 million charge related to writing down the value of deferred tax assets, the company earned 6 cents per share. Analysts surveyed by Thomson Reuters on average expected adjusted per-share earnings of 5 cents on revenue of $53.2 million.

For fiscal 2009, Ixia had a net loss of $44.2 million (-70 cents), 178 percent higher than in 2008. Revenue rose only 1 percent to $178 million.

Shares closed down 31 cents, or nearly 4 percent, to $8.10 on the Nasdaq.