"We are continuing to have cooperative discussions with the Department of Justice about this arrangement and voluntarily delayed implementation for three and a half months in order to give them time to understand the agreement. That process is continuing exactly as expected," a Google spokesman said.
Yahoo announced last month that Google would start powering a small portion of paid search ads on Yahoo properties. The deal, part of Yahoo's attempts to fend off Microsoft's takeover bid, is expected to bring in up to $800 million in revenue for Yahoo. When the deal was announced, Yahoo and Google said they anticipated that the federal authorities would investigate whether the arrangement ran afoul of antitrust laws.