Could the fact that a lot of US companies book profits overseas and keep them there for tax reasons foil your assumption about the meaning of a high US market cap:domestic GDP ratio?
Good point. I'd wager that US listed companies' share of profit and/or income growth outside of the US has increased since the 70s/80s. I'd at least have a global crosscheck of some kind.
That is already implicit in the Efficient Market Hypothesis' valuation of the total market capitalisation of stocks (that is part of the reason for which the total value of the stock market exceeds GDP).
Right, but this chart ignores that (as far as I can tell). If US listed companies are going to eat more of the global GDP, then it wouldn't be crazy that the value of the stocks will exceed GDP of the country in which it's listed (i.e., the fact that the value does exceed GDP might not be a precursor to a crash).
There's really no reason why GDP should equal market cap. Companies are largely (especially now, since interest is so low) valued on future income, rather than current income.
Look at Amazon and Netflix, both tradin at 200x earnings. This is beacuse investors think they will earn a lot more in the future than they do now. Are they overvalued? who knows.
Indeed, market valuation as a multiple of GDP is hitherto unknown to me. However that's why I wrote partially: foreign assets are factored into the value investors attribute to the stock market as a whole. In retrospect I shouldn't have argued from the standpoint of percentage of GDP.
