Travel search engine Kayak.com has pulled down $196 million in one of the largest venture rounds of 2007 to acquire rival SideStep, the companies announced Friday.

The financing round was led by prior investor Sequoia Capital, whose partner, Michael Moritz, will join the Kayak.com board of directors. Also, participating were previous Kayak investors General Catalyst Partners and Accel Partners, SideStep investors Norwest Venture Partners and Trident Capital and new investors Oak Investment Partners and Lehman Brothers Venture Partners. The round also included debt from Silicon Valley Bank and Gold Hill Capital.

"It's an extraordinary amount of money to raise," Kayak co-founder and Chief Technology Officer Paul English said. "It's more than a lot of tech IPOs raise."

The acquisition of SideStep accounted for more than $150 million of the venture funding with exiting SideStep investors tapping additional funds from the company's cash horde. Kayak previously had raised $30 million in three venture rounds.

Mr. English said the courtship began about a year ago when SideStep approached Kayak about a 50-50 merger of equals. Though the initial talks cooled, Kayak resumed contacts in November as its strategy crystallized.

"As we looked at our plans to become the No. 1 travel site, ultimately the best way to get qualified traffic is from someone who has almost identical traffic," he said. "It's a scale play."

The company plans to maintain both travel search brands while consolidating some of the technology under the hood. Mr. English said that Norwalk, Connecticut-based Kayak would retain its minimalist, Google-like approach to search, while SideStep, with its hotel reviews and travel guides, would continue to offer a rich-media aesthetic closer to Yahoo's.

Mr. English declined to specify what valuation was accorded to Kayak in the funding deal, but he said dilution was minor and that Kayak will record about $50 million in 2007 revenue while SideStep will notch about $35 million. Both companies are profitable, he added.

Kayak forecasts that the merger will bump the number of searches on its sites to 33 million in January, more than double the 16 million in January 2007.

Santa Clara, California-based SideStep has raised more than $30 million in funding from Trident Capital, Norwest, PAR Capital, Saints Capital, and Leader Ventures.

Kayak and SideStep are both meta-search engines that scour travel deals on flights, hotels, and rental cars from online agencies, consolidators, and the sites of airlines, hotels, and car rental companies.

Kayak is taking aim at Expedia, the No. 1 web site based on travel searches per month, Mr. English said. At the same time, Kayak partners with Expedia by referring searchers to that site, which serves as a ticket-selling agency. He likened the relationship to a shopping search engine like shopping.com and a retailer like BestBuy.

In addition to greasing the acquisition, the venture round will help fund international expansion.

Mr. English said Kayak's revenue is 95 percent domestic with most of the remainder coming from the United Kingdom. In 2008, the company plans to add to its European sites in France, Germany, Spain, and Ireland, and roll out new sites in India and China with the hope of eventually generating more than half of its business from foreign markets.