am I correct in thinking that some things you don't sell to outsiders? For security reasons at least...stock markets are pretty much everything in a modern economy.
There are 8 nuclear powerstations currently operating in the UK, and they are all owned and managed by EDF Energy, the UK subsidiary of the French state owned EDF.
Obviously there is a large difference between French and Chinese state owned companies
Countries have bespoke rules as to how they utilize outside help, everything from merely purchasing the source code and running & operating themselves to fully outsourcing everything.
Outside of US equities, most other worldwide markets are pretty tiny as far as transaction volume goes.
Meanwhile the NYSE is owned by ICE with tons of EU operations after buying Euronext (ie: Paris and Amsterdam to name 2).
Nasdaq owns a bunch of Baltic and Scandinavian exchanges.
The Boursa Italia isn’t exactly a juggernaut in EU/world terms.
And there’s lots of exchanges for Italian companies to list on if they want good access to their shares (e.g. Ferrari cross listed in NY).
For euro based exchanges the ship has largely sailed even with where their corporate parents are based with giant impactful exchanges like Liffe being owned by external companies.
Recently (2016) in the UK SoftBank's acquisition of Arm was at least somewhat controversially approved; it was by no means a done deal just because SB offered and shareholders agreed.