SAN FRANCISCO  Google had little desire to own a premium slice of the nation’s airwaves, but a week into a federal auction for wireless licenses, it found itself at risk of being the winning bidder for the coveted spectrum.

The spectrum would have cost $4.7 billion, Google’s biggest single investment. Winning would have thrust the company into the wireless business and could have sent Google’s battered shares even lower.

Google and other companies began publicly discussing some of the auction’s behind-the-scenes action after an anti-collusion rule prohibiting participants from commenting was lifted Thursday. Google bid in the auction to honor a promise made to the Federal Communications Commission.

Last summer, the company vowed to bid a minimum of $4.6 billion, the reserve price, for a set of frequencies known as the C block as long as the F.C.C. imposed some “openness” conditions on it. The F.C.C. imposed two conditions, requiring the owner of the spectrum to open its network to devices and services from third parties.