It makes some sense if you consider market caps to be expectation of returns. All other things being equal (like the percentage of the GDP made by publicly trad

It makes some sense if you consider market caps to be expectation of returns. All other things being equal (like the percentage of the GDP made by publicly traded companies) it makes sense to expect the market to expand at about the same speed as the GDP. That this ratio doubled in 8 years is worrisome. The thing is that an alternative analysis is to look at the linear regression since 1980 and it seems clear that a background upward tendency does seem to exist, so we can see 2009 as an adjustment to the 2008 crisis and 2017 as only slightly above the expected trend.