Some more information that was never meant to be made public has been revealed in the Microsoft v FTC court battle.
In the same email and documents revealing Xbox had a huge list of companies it was considering acquiring, page 10 reveals Ninja Theory was purchased for the sum of $117 million USD.
Again, what's interesting about this is it was never meant to be publicly revealed. There's also a date of June 10th, 2018 attached, which is seemingly when the deal went through. This apparently lines up with E3 2018 when Xbox announced it had acquired the Forza development teams as well as Undead Labs (State of Decay) and Compulsion Games (We Happy Few, South of Midnight).
Ninja Theory is currently hard at work on Senua's Saga: Hellblade II, which is scheduled to launch day one on Game Pass and Xbox platforms, next year.