I second that. In addition, most of those companies use a portion of their revenue to buy back their shares, pushing their price up. So, the value created worldwide ends up growing the US stock market.
Staying out of whether or not the concentration is a problem at the national/international level, is there any realistic alternative short of massive protectionism a la China to force home-grown tech companies in other parts of the world?
America is NOT the largest market the EU is MUCH BIGGER. And it is not "America" that commercialises technology, but a small portion of California called The Valley.
https://statisticstimes.com/economy/united-states-vs-eu-econ...