It's honestly surprising when you remember that Nintendo does NOT own certain studios who have worked for them for a long time. For one, and linking to this image in fact, did you know Nintendo doesn't own HAL Labs? Yeah Nintendo doesn't own the company Sakurai and Iwata came from. Next Level Games also worked with Nintendo for over 15 years before Nintendo finally bought them, and it seems like Nintendo's main motivation for doing so is because the old share holders for Next Level were gonna sell their majority stocks and Nintendo bought them mostly to ensure Next Level can still work with them (I guess maybe the Stamper brothers selling the majority of their stock in Rare to Microsoft back in 2002 does maybe haunt some of Nintendo's higher ups, meaning it's legit possible the only way Nintendo might finally buy HAL is if HAL is at risk of having its majority stocks bought by someone like Sony or Microsoft). And before Next Level their previous company purchase was Monolith Soft, mainly because Namco didn't want 'em anymore so Nintendo bought the stocks from Namco, and it turned out it was a majority stock to boot.

Nintendo doesn't even fully own Game Freak, they own a good chunk of Game Freak, but not fully.