How exactly would a foreign power block two US companies from merging when it has no significant stock holding in either?
It would be tricky, though, because my sense is that China still needs Intel/Qualcomm more than they need China. At the same time, it would be pretty deadly to be denied access to that market and your products subject to excess tariffs if imported by others.
In practice, yes, as you point out: US firms must have assets in Europe to compete effectively.
But even if they didn't, Europe could deny access to the European market. So there is no reason to try and minimize surface in Europe. e.g. Apple has to comply with European antitrust rulings about app store access, even if Apple were to just sell their product to third party distributors in Europe and not have any presence in Europe.
Not really, Apple would just get customers the same way they’re sold in any other part of the world that doesn’t officially have iPhones (i.e. Russia), the EU doesn’t have the authority to seize shipments purely based on a violation of the DMA.
I think it goes like this: The major market regulator could say directly/indirectly: Hey you can merge in the US ... but good luck operating in our geography in a frictionless manner if we are against your merger. As a regulator we can make life hell for you if you don't obey our anticompetitive laws. Since you derive a high percentage of your revenue/profits you must listen to us !
It all depends on the percentage of sales in the foreign geography. With EU/China it can be quite high -- especially for tech companies.
So yes, foreign powers can and often do block companies from merging.
CEO to board: We want to acquire $LESSER_COMPANY, but China opposes. We can go through, but we'll lose easy access to that market, and in net terms our valuation will drop.
Board: Forget it.