Priceline.com to Buy Kayak for $1.8 Billion Just months after going public, Kayak Software has been snapped up by a rival. On Thursday,Priceline.com, a travel company from an earlier Internet age, announced that it would buy Kayak, its younger competitor, for $1.8 billion. Under the terms of the cash-and-stock deal, Priceline agreed to pay $40 a share. The price represents a 29 percent premium over Kayak's closing price on Thursday. "We're excited to join the world's premier online travel company," Steve Hafner, Kayak's chief executive, said in a statement. Kayak announced the deal as it reported earnings on Thursday. The company said it generated revenue of $78.6 million in the third quarter, an increase of 29 percent from the period a year earlier. Its net income rose 14 percent to $8 million. Kayak's stock has risen since its I.P.O. in July, in which its shares were priced at $26 apiece. The company had a long journey to the public markets, after initially filing to go public in 2010. "Kayak has built a strong brand in online travel research and their track record of profitable growth is demonstrative of their popularity with consumers and value to advertisers," Jeffery H. Boyd, Priceline's chief executive, said in a statement. We believe we can be helpful with Kayak's plans to build a global online travel brand.