Can we consider CBS a monopoly?

Can we consider CBS to have a monopoly over the NCAA tournament? They are the only network allowed to show games. They are making tons of money through commercials for these games and their ratings are going through the roof.
It has been said that America's production goes down by something like 8 billion during this week. People actually fake being sick to stay home and watch these games. I myself set up two televisions in the living room and watch two games at one time.
The tournament isn't just about watching your favorite team.
I love Duke but if they are up 15 I will switch to a closer game.
We have seen a ton of wonderful games already in this tournament and a lot of great upsets. I hope it continues on.