NBC can dictate race times after paying billions for broadcast rights through 2032
While it is the International Olympic Committee that draws up the schedule, there is no bigger influence than NBC Sports. It has paid $7.75 billion US, in exchange for the American broadcast rights to every Games through 2032. That's more than every other broadcaster has paid the IOC combined. At that price, you get a lot of influence.
The United States is the largest television market in the world — and has a clear interest in seeing key sporting events broadcast when the most Americans can see them. The five key sports, those with typically the highest viewership, are mostly held to accommodate American prime time. Swimming, beach volleyball and track and field are latest, often not until 11 p.m. Rio time (10 p.m. on the U.S. East Coast). The two others, gymnastics and diving, happen slightly earlier.
And it's not just a question of the time of day. NBC has the power to affect which month the Olympics are held. For instance, when Beijing first bid for the 2008 Games, they'd planned a mid-September start. When NBC heard of the plan, they saw a challenge to seizing as many American eyeballs as possible.
"There's NFL coverage on Sundays and Mondays, and college football is now on four or five nights a week," the then-chairman of NBC Sports Dick Ebersol told the New York Times. "All of that goes away if you start in mid-August."
NBC explained that to the IOC and, lo and behold, when Beijing held the Games, they began on Aug. 8. Many assumed the mystical importance of the number eight in Chinese tradition was a factor — the Games started on 8/08/08.
https://www.cbc.ca/news/world/rio-olympics-nbc-late-races-1.3715538