If you're looking for a rooting interest in the upcoming Super Bowl between Seattle and Denver, here's why you may want to consider cheering for the Seahawks.

A bizarre theory known as the "Super Bowl indicator" says that, more often than not, the market will post a gain if the team from the NFC wins the Super Bowl.

It sounds crazy, sure, but it's been surprisingly accurate over the past 47 years. Howard Silverblatt, senior index analyst at S&P Dow Jones Indices, told USA Today that the Super Bowl indicator has been correct in 37 instances, or nearly 80 percent of the time.

"It is a totally irrelevant and irrational indicator," Silverblatt said, "but it works."

There are some quirks in the formula. For example, certain AFC teams are considered NFC teams by the indicator. The Baltimore Ravens are one such squad because the franchise, formerly the Cleveland Browns, was part of the NFL before the NFL and AFL merged in 1970. So when the Ravens won the big game last year and the stock market rose, it counted as a win for the indicator.

The Super Bowl indicator has worked in four of the past five years, with the notable exception being 2008. The New York Giants won the Super Bowl that year but several months later the stock market crashed.