I think, most realistic evaluation is classic VC "divide year sells by bank deposit percents", nothing less and nothing more. So, as example, NASDAQ have about 7.4B sales and divide by 5% will be somewhere about 140B (link below).
I think this approach most realistic, because it use very simple and easy to get input data and don't need sophisticated logic to separate debts.
Unfortunately, I remember statistic S&P from 2008, from all NASDAQ only Microsoft had fully 100% coverage of all debts (so AAA rating), not just 1 year of percents as all others.
For other things exist commodities exchange, etc. Just calculate sum of all exchanges and will got good enough approximation.
And I don't think it is worth to use more deep logic, because will need to spend much more time and resources to gather data, and will achieve basically same, but delayed to few months or more.
Only exclude, it may worth to get somewhere survey of households economy, as they are much more conservative than business, so data from 3-5 years ago will be good enough for first look.
I think this approach most realistic, because it use very simple and easy to get input data and don't need sophisticated logic to separate debts.
Unfortunately, I remember statistic S&P from 2008, from all NASDAQ only Microsoft had fully 100% coverage of all debts (so AAA rating), not just 1 year of percents as all others.
For other things exist commodities exchange, etc. Just calculate sum of all exchanges and will got good enough approximation.
And I don't think it is worth to use more deep logic, because will need to spend much more time and resources to gather data, and will achieve basically same, but delayed to few months or more.
Only exclude, it may worth to get somewhere survey of households economy, as they are much more conservative than business, so data from 3-5 years ago will be good enough for first look.
https://www.macrotrends.net/stocks/charts/NDAQ/nasdaq/net-wo...