The deal will see Google sell some of the ads displayed alongside search results on Yahoo's Web site. Yahoo embraced the idea as an alternative to a takeover by Microsoft Corp.

The Justice Department is already examining the deal to decide whether to intervene. In a letter Thursday, Wisconsin Democrat Herb Kohl, chairman of the Senate Judiciary antitrust subcommittee, said his panel concluded that "important competition issues are raised by this transaction." He urged the Justice department to "continue to monitor the state of competition in this industry."