We knew this was coming. The Justice Department has begun a formal antitrust investigation into the search advertising agreement recently announced between Google and Yahoo. But other internet companies will be required to provide documents, according to the Washington Post. The move is thought to indicate a closer scrutiny than originally expected.
Lawyers told the Post that the demand for documents from other companies suggest that Google-Yahoo deal will be reviewed by those higher up in the antitrust division of the DOJ.
Still, the investigation should come as no surprise. When Yahoo was running a test of Google's ads back in April, the Justice Department investigated. However, they were notified of the test ahead of time.