If it's not a MS acquisition it's probably Embracer honestly, Embracer been buying up everything.
The majority of Embracers acquisitions have been small studios though, imo only Saber Interactive, 4A Games and Flying Wild Hog have been newsworthy acquisitions so far.
You're forgetting their biggest one, which was Koch Media/Deep Silver.
They're building cash too, in 2020 they raised $812m in total for the specific purposes of acquisitions.
They've also confirmed recently that they're in talks with over 100 developers, big and small, including publishers for acquisition purposes.