• There’s no love lost between Elon Musk and Mark Zuckerberg. 
  • The CEOs have been feuding since 2016, when a SpaceX explosion destroyed a Facebook satellite.
  • Since then, they’ve butted heads repeatedly. Now they’re threatening to face off in a cage match.

For over six years, two of techs biggest names — Elon Musk and Mark Zuckerberg — have been caught up in a feud, clashing over topics like artificial intelligence and rockets.

The two men have been griping about each other behind closed doors for years, according to The Wall Street Journal. But the tech moguls haven’t exactly kept their rivalry a secret from the public, either.

When a rocket from Musk’s SpaceX exploded and destroyed a satellite from Zuckerberg’s Facebook in 2016, Zuckerberg issued a heated statement, saying he was “deeply disappointed” about SpaceX’s failure. And when Facebook became embroiled in the Cambridge Analytica scandal, Musk publicly deleted his companies’ Facebook pages, tweeting that the company gave him “the willies.”

Most recently, the two men have threatened to make their fight physical and face each other in a cage match.

The two billionaires are among the richest people on the planet, placing them in an elite circle, even by Silicon Valley standards. Even though both dabble in artificial intelligence and social media, and their companies have partnered in the past, it seems there’s no love lost between Musk and Zuckerberg.

Here’s where their feud began and everything that’s happened since.