What percentage of profits in the S&P 500 index do you think comes from outside the United States? The nice thing about S&P 500, EuroSTOXX 50, and Nikkei 225 indices: A huge portion of their profits come from outside their home regions: US, EU(rope), Japan. Think: FAANG, Microsoft, Intel, AMD, NVidia, HP, Ford, Boeing, Phillip Morris, Tesla, Siemens, EADS, Phillips, NXP Semi, Alstom, ABB, SAP, Santander, Volvo, Volkswagon, Hitachi, Panasonic, Toyota, Kyocera, Nintendo, Sony, etc. Upon closer inspection, they act like international indices. Don't bother with indices focused upon developing economies -- they are already covered by the Big Three indices!

My take: Of these Big Three indices, the S&P 500 will outperform others over the long term. That is not blind pro-US bias. The US economy (and, correspondingly, the S&P 500 index) is much more dynamic than EU and Japan. It can recover faster after downturns -- recessions & depressions.

<snark> As a retail investor, put your money into a very low commission ETF that tracks the S&P 500 index. See: Fidelity, State Street, or Vanguard. Enable dividend reinvestment programme ("DRIP") to buy more shares with dividends. Go to sleep for 30 years. Wake up rich. Simples. </snark>

You can trade shares of companies from all around the world on US stock exchange.