Google Rivals Are Readying An Antitrust Assault

In a preview of Wednesday's Senate antitrust hearing on whether Google abuses its dominance on the Web, representatives of the sites—which help people search for information on consumer goods, local businesses and airline flights—said in interviews this week that Google has increasingly sought to drive people who use its search engine to its own specialized sites that compete with theirs.

One of the companies, Nextag, is going even further. Chief Executive Jeff Katz said Google also prevents his company's site from bidding on the prominent ads that show up next to search results for products such as running shoes. Instead, he said, because Google sees his company as a threat, Nextag can only bid to appear in text ads lower down on the results page, limiting its exposure to consumers.

"Google is the dominant digital advertising resource in the world, and Nextag is restricted from marketing itself to shoppers about the services we can provide," said Mr. Katz, whose site helps consumers comparison shop for electronics, home goods and other products.

Google has long denied that it profits by punishing other sites on its search engine.