Half a billion dollars in commercial time.

While it has never been easier for advertisers to reach vast numbers of people around the world, thanks to the internet, the lure of the Super Bowl is the one huge audience it provides. Advertisers spent a combined $534 million on ads before, during and after the game last year, according to the research firm Kantar. The company said that the roughly $5 million a 30-second commercial cost last year compared to $2.5 million for 30 seconds in the National Football Conference championship game and $1.9 million for the same time in the Academy Awards.

“It’s a finite amount of inventory,” Gibbs Haljun, managing director of media investment at GroupM, the media buying arm of WPP. “There’s only one game, it’s only on once a year, the ratings are relatively stable and it is what it is.”

Still, it appeared that NBC was selling at least some spots down to the wire, as illustrated by a last-minute buy from Wix.com that the company announced on Friday. In January, Wix.com was promoting its decision to sit out of this year’s game and arranging press interviews with its chief marketing officer about alternative plans for the money.

NBC said in an email late Friday that it had sold all of its ads for the game.

The network, which is owned by Comcast, has had the dual challenge this year of selling ads for both the Super Bowl and the Winter Olympics, which will begin on Friday.

“I can’t remember the last time that occurred,” Mr. Haljun said, “so this is kind of an odd challenge for them and continues to make the negotiations a little more interesting and robust.”