[sidkshatriya]

Major markets like EU and China often do have a major influence on mergers even though the companies merging could be based in the US and most shareholding could be US.

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.

[ASalazarMX]

And I think it ends like this:

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.