NBC has sold over $1 billion in Olympics advertising - and it's on track to hit an all-time sales record

NBCUniversal has sold more than $1 billion in advertising spots during its upcoming broadcast of the Summer Olympics starting in August. At this pace, the media company will set an all-time sales record.

"The value of live, big-event programming is more important than ever to advertisers because of its ability to reach large audiences," said NBC Sports' Executive Vice President of Advertising Sales Seth Winter in a blog post.

For companies still looking to get a piece of the valuable ad time during the sporting event, Winter said, "Some of the most valuable inventory is gone; but, there is still some primetime availability on the network as well as cable-channel inventory."

For the 2012 London Olympics, NBCU didn't reach $1 billion in ad sales - including national broadcast, cable, and digital sales - until July 25. That was two days before the opening ceremony. Currently, there are 129 days until the Rio Games' opening ceremony on August 5.

Why the rush to buy advertising?

Due to Rio being just one-hour ahead of the East Coast, more games will be broadcast live this summer compared to the London games, which was recorded much of the time and aired later. That potentially means the 17-day broadcast will be watched by more Americans and could exceed the London games' already huge average of 31.1 million viewers over its 16-day run.