TV ratings for the National Football League have declined in each of the past two seasons.

RBC Capital Markets says that this is going to hurt ad sales as investors shy away in an increasingly competitive landscape.



When it comes to TV ratings, the National Football League needs a Hail Mary.

Average game viewership has fallen to 15 million this season, down from 16.5 million last year, and the lowest since 2008, according to data compiled by RBC Capital Markets.

The firm also finds that the league's audience is down on a year-over-year basis, and notes that it hasn't seen meaningful growth since 2013, when the measure climbed 5%. RBC says this has had an adverse effect on how advertisers view the prospect of buying time slots during NFL games.

"The sustained decline is what worries investors about media's willingness to offload the NFL's monetization risk," analyst Steven Cahall wrote in a client note.

NFL viewership has been on the decline. RBC Capital Markets

RBC says possible reasons for the ratings skid include player protests, the NFL's ongoing concussion controversy, competition from politics, increased offerings from cable and entertainment providers, and an oversaturation of games. And there's also what Cahall considers to be the most obvious explanation:

"When a Sunday or Monday Night game is 42-7 late in the 3rd quarter, the viewer may now opt to catch up on Stranger Things or Billions instead of watching through to the end," he said. " Five or ten years ago, an unexciting 4th quarter might still have been the best thing on TV."