Best approach to invest is based on real market size and influence.
Why?
US now only about 30% of world GDP...
U.S. GDP is just shy of 24% of global GDP, actually, and without Purchasing Power Parity adjustment. But "so what?" (as we'll see in a moment).
...so you should not have >30% of your total wealth invested in US stock market or SPY (if you believe in proper diversification).
U.S. stock markets are not the real U.S. economy. They are stock markets, the New York Stock Exchange and the NASDAQ, where the stocks of businesses happen to be listed and traded, per U.S. regulations (primarily the U.S. Securities and Exchange Commission, one of the oldest if not the oldest regulator of its kind). Those businesses are headquartered all over the world and do business all over the world, hopefully with the exception of internationally sanctioned countries such as North Korea. Their stocks just
happen to be listed and traded in New York.
Historically, traditionally, stock market locations aligned pretty well with real business activities and national economies. That's not true any more, and to the residual extent it's true it's becoming progressively less true. As only one example, the fast food company that
seems truly American, McDonald's, is still headquartered in the United States but now does about 2/3rds of its business outside the United States.
VWRA owns total portfolio contains >50% in US stock market but US GDP only 30% of world total GDP.
I think VWRA is too much overweight US stock market! I would be wary!
I wouldn't. New York is
the place where global businesses want to list their stocks, even businesses that are not headquartered in the United States and don't do much business in the United States. New York is also the world's leading city for international diplomacy since it's the headquarters city of the United Nations. I suppose you could visit some other random city, such as Casablanca, to attempt to practice international diplomacy, but you're probably not going to have as many ambassadors to talk to there. They have to meet regularly
somewhere, and they meet in New York, even when they talk about regional trade in East Africa, for example.
If you want to invest in the entire world's commerce in any feasible, approachable way, you're going to rely heavily (directly or indirectly) on the stock markets that happen to be located in New York. Analogously, if you're in the ocean shipping and/or ocean cruise business, you're going to be dealing with vessels that are flagged in Panama. Most of those vessels will never even visit Panama, but that's the most popular flag of convenience. If you're a diamond trader then your short list includes New York, Antwerp, and (fairly recently) Dubai. Tuna for sushi? Definitely Tokyo. Filmed and broadcast entertainment? Hollywood (Los Angeles). Fine art? New York and London. Fashion? New York, Paris, and Milan are among the global leaders. Commodities, such as wheat, coffee, sugar, corn, and cotton? Chicago is on your short list. Practically anything/everything Internet- and technology-related? The San Francisco Bay Area, California, U.S.A. And so on. Global marketplaces still need one or a couple locations, and the fact buyers and sellers come to meet in a particular location doesn't make those markets any less global, especially nowadays with electronic trading.
Here's an interesting question: is Singapore a leading global marketplace for something, anything? Could it be?
Generally speaking, you should neither penalize nor reward stocks based on where they happen to be listed and traded.