Contract is now worth 503 with 473 "guaranteed"
Ian Rapoport @RapSheet
The #Chiefs and QB Patrick Mahomes have agreed to terms on a 10-year extension worth $503 million, sources tell me and @TomPelissero. He gets $477M in guarantee mechanisms and gives the ability for Mahomes to have outs if the guarantee mechanisms aren’t exercised. No trade clause
That sounds like the Chiefs are not on the hook for $477M, just if they want to keep him for the duration of his contract then that's what they're paying him.