According to Sports Illustrated, Rey Mysterio is currently negotiating with both WWE & Global Force Wrestling about coming into each promotion following his time with Lucha Underground. Mysterio is currently signed with Lucha Underground through the end of the third season, ending in September. He would then reportedly be free to work with any company after his 90-day non-compete clause expires. While there is always a chance Lucha Underground could offer Rey a new contract, with no fourth season announced, that seems unlikely at this time.
While signing with WWE would obviously signal a return to the promotion where Rey Mysterio saw much of his greatest success, GFW would provide a new challenge for Rey, as he’s never worked for the company. Rey also has ties with current GFW Champion Alberto El Patron, although El Patron’s own standing with the company currently is unknown due to Patron’s pending legal issues.