What is there to say about the inverted yield curve that hasn't been said already?

The yield spread between three-month and 10-year Treasuries fell below zero on Friday for the first time in more than a decade. It's arguably the most significant inversion yet because such a move has accurately predicted the past seven recessions. So, yes, it's true: The world's biggest bond market is calling for a economic downturn in America's future.

Some caveats before investors sell everything. While this is the first time the curve has been inverted since 2007, during the last cycle, the spread first fell below zero in January 2006, almost two full years before the start of the recession. If history repeats itself, that means traders can pencil in the next slump for late 2020 or early 2021. That's still a lot of time for riskier assets to outperform, or for the economic outlook to improve.