Updated from 9:58 a.m. ESTNetwork-gear maker F5 ( FFIV) was a welcome gainer in Thursday's grim market, jumping 11% after posting sharply higher earnings and revenue in the fourth quarter. The Seattle tech outfit earned $10.0 million, or 26 cents a share, in the quarter, compared with earnings of $3.8 million, or 11 cents a share, last year. Pro forma to regularize the small company's tax treatments, F5 earned $6.8 million, or 18 cents a share, in the quarter. Revenue jumped 66% from a year ago to $60 million. Analysts had been forecasting earnings of 21 cents a share on a basis that is comparable to the company's bottom-line profit of 26 cents a share, according to Thomson First Call. F5 said operating margin swelled to 24% in the December quarter, up from 11% a year ago. The company said revenue growth was driven by continuing strength in its core traffic management business across all geographic regions. In the second quarter, F5 expects to earn 28 cents or 29 cents a share on revenue of $63 million to $65 million. Analysts were calling for earnings of 23 cents a share on revenue of $56.6 million. The stock added $5.03 to $49.72 Thursday.