[whatever1]

So let’s say I am eu citizen I own a data center company in Brussels.

I sell 1 stock to MS USA. Can they at any point demand all my data ?

[ahi]

They can try, but presumably as a tiny shareholder you would tell them to go f themselves. Subsidiaries don't have that luxury.

[danielheath]

The laws I have read used the term “effective control”; if a shareholder is able to control the org (eg can replace the CEO or board), they are obliged to comply with government orders regarding that org.