Recently it was announced that David Vongries was selling the Kirki Customizer Framework. Themeum has stepped up to purchase it. They are the company behind TutorLMS and Qubely.

The founders of Yoast have invested in WPCS, which is a multitenancy, scalable WordPress as a Service or Software as a Service hosting platform. My understanding of how the service works is that your sites share a WordPress files install but each site has a different database.

The MemberPress blog posts news of the acquisition of Wishlist Member and CourseCure by Caseproof. They also recently acquired MemberMouse.