https://www.forbes.com/sites/timworstall/2011/06/28/gdp-for-...
GDP to market cap is worse. The net worth of a country is not it's GDP. The total wealth of the US is about ~90 trillion.
https://en.wikipedia.org/wiki/Wealth_inequality_in_the_Unite...
The estimates for total wealth, however, are really fraught and fluctuate, as does market cap in other currencies.