At that level you typically set up what's referred to as a "family office" https://en.m.wikipedia.org/wiki/Family_office https://en.m.wikipedia.org/wiki/Family

At that level you typically set up what's referred to as a "family office" https://en.m.wikipedia.org/wiki/Family_office https://en.m.wikipedia.org/wiki/Family_office The family office will manage the investment portfolio, typically across not only brokerages and banks but also direct investments / private equity/ vc / etc.