I gotta stick up for Hall on this. He's said in interviews on basically every podcast he's been on (Open Mat Radio, BJJ Brick, GrappleArts the list goes on), on his DVDs, and I've even heard it from him in person.
He always tells the story the same way. He learned the position from Brandon Vera while training at Team Lloyd Irvin. Brandon Vera saw it/learned it from Dean Lister who used it ADCC 2003.
The GIF of Lister doing it in 2003 is here.

All Ryan Hall says is that he was the first to call it the 50/50. He and everyone else knows that it was done long before him. he called it the 5050, Lloyd went crazy with the marketing, and it just started getting known as the 50/50. Ryan helped popularize the 50/50 for heel hooks in no-gi and the Atos gang (such as the Mendes brothers and Bruno Frazzato) really popularized the position in the gi.
He didn't invent it and he's never said he did.
He always tells the story the same way. He learned the position from Brandon Vera while training at Team Lloyd Irvin. Brandon Vera saw it/learned it from Dean Lister who used it ADCC 2003.
The GIF of Lister doing it in 2003 is here.

All Ryan Hall says is that he was the first to call it the 50/50. He and everyone else knows that it was done long before him. he called it the 5050, Lloyd went crazy with the marketing, and it just started getting known as the 50/50. Ryan helped popularize the 50/50 for heel hooks in no-gi and the Atos gang (such as the Mendes brothers and Bruno Frazzato) really popularized the position in the gi.
He didn't invent it and he's never said he did.