An indicator based on the belief that a Super Bowl win for a team from the old AFL (AFC division) foretells a decline in the stock market for the coming year, and that a win for a team from the old NFL (NFC division) means the stock market will be up for the year.

Chalk it up to coincidence, but this indicator has been surprisingly accurate (around 85% correct) over the past years. Even so, you probably shouldn't bet the farm on it.