Here's a very, very rough ballpark estimate based on your data: - $2.7T in market cap - let's say average P/E ratio is 25 (P/E is approximately the ratio of

Here's a very, very rough ballpark estimate based on your data: - $2.7T in market cap - let's say average P/E ratio is 25 (P/E is approximately the ratio of company valuation to annual profits) - let's say the profit margin of a typical tech company is 20% - let's say 40% of a typical tech company's revenue is in the US Estimated US revenue of the companies in your spreadsheet: $2.7T / 25 / 0.20 * 0.40 = $216b (about 1.5% of GDP, which is still huge) By the way, I think your initial estimate of the total market cap of companies signing the brief is quite useful and informative, it just shouldn't be compared to GDP :)