That's a much better metric, but there's still a lot missing from it. That's only publicly traded companies, that doesn't account for all assets, both privately and publicly owned. Alaska's oil reserves, farmland, mineral deposits, existing factories, highway infrastructure. These are all examples of valuable assets that, while much of it is in the hands of publicly traded companies, most of it is not. Total valuation for a country is a hell of a lot more than just the valuation of it's stock market.