Priceline.com ( PCLN) said two acquisitions helped lift third-quarter revenue nearly 10% from a year ago, and the online travel service company's net income was sharply higher thanks to a big tax gain.

The Norwalk, Conn., company beat Wall Street's earnings estimates, sparking an after-hours rally, but offered fourth-quarter guidance that, at best, was in line with expectations.

Revenue in the third quarter totaled $258.8 million, up from $235.9 million a year ago. The latest results include the acquisitions of Active Hotels and Bookings B.V. Gross travel bookings were $611.1 million, up 40% from the third quarter of 2004.

When calculated according to generally accepted accounting principles, the company earned $170.6 million, or $3.71 a diluted share, including a $160 million noncash tax benefit. Priceline earned $9.3 million, or 23 cents a share, a year ago.

Excluding items, Priceline had a profit of 47 cents in the third quarter, 10 cents above the consensus estimate carried by Thomson First Call and up from 28 cents last year.

The company projected an adjusted profit of 24 cents to 28 cents a share for the fourth quarter, vs. the mean estimate of 28 cents. Still, full-year earnings should be $1.33 to $1.37 a share before items, topping expectations.

Additionally, Priceline's board gave the company the authority to buy back up to $50 million worth of its common stock.

Shares soared $2.54, or 13%, to $22.04 in after-hours trading. They finished Wednesday's session down 4 cents at $19.50.