March Madness ratings have been fairly static the last four years, but revenue for CBS’s annual NCAA men’s basketball tournament has been anything but.

Ad sales for the three-week tourney starting March 20 are projected to hit a record $545 million this year, up 5 percent over $519.6 million last year, according to a new report from TNS Media Intelligence.

Since 1998, annual spending on the tourney has more than doubled from $239.1 million, while the number of total advertisers has increased by 56 percent, going from 81 to 126 last year.

NCAA basketball ranks No. 2 among all postseason sporting events in revenue, behind only the National Football League’s lucrative playoffs, which generated $643 million last year.

March Madness is well ahead of the rest, with baseball’s playoffs ranking third at $322 million, the National Basketball Association playoffs fourth at $279 million, and college football’s bowl games fifth at $242 million.

The average price for a 30-second spot in the NCAA championship game was $1.26 million last year, topping all but a Super Bowl ad spot, at nearly $2.4 million.

Even early-round games had one of the higher ad rates at $689,000, well ahead of the NBA finals at $389,000, World Series at $425,000 and even NFL divisional playoff games at $531,000.

The continued rise in prices comes at a time when ratings for the 64-game playoff have been relatively static, both in the championship game and the early rounds. Not withstanding a spike in 2005, when popular North Carolina won the title, the championship game’s rating has hovered around a 10.0 in households, well down from past years but still a strong showing in an increasingly fractured TV environment.

What advertisers like about the tourney, and what keeps them coming back at a very high annual retention rate of 81 percent, is its reach. Roughly 130 million people tuned in to some part of the tournament last year, while 40.3 million caught all or some of the championship game.

Much of that interest is driven by the industries that have sprung up around the games, such as NCAA office pools and fantasy sports games.

Some of the ad revenue, however, is coming from a totally new source, online viewing. CBS will make free feeds of every game available for the third year, and while this viewing accounts for barely 1 percent of the total audience for the games, it is growing.
CBS more than doubled its online revenue for the tournament last year.

Much like the Super Bowl, where Anheuser-Busch dominates the total ad spend year in and year out, General Motors has been the most dominant March Madness advertiser for several years. From 2003-’07, the car company spent an average $70.2 million, compared with $22 million for No. 2 Coke.

This year’s college hoops tournament kicks off at noon on March 20 on CBS. The field of 65 teams will be set Sunday, with a play-in game on ESPN two days earlier.