MGM’s relationship with Hyatt ends September 30. They were partners for 10 years, and MGM had recently groused about not seeing as much value as they could they could achieve from the partnership.
Now we know what they were working on as a replacement: Marriott Bonvoy members will earn and redeem points at 17 MGM resorts starting in October, and bookings of MGM properties will be available through Marriott channels by end of year.