> 4 out of 5 of the largest companies on earth are tech firms Tech isn't really an industry... Amazon = Retail (and probably another 10-20% software and softw

> 4 out of 5 of the largest companies on earth are tech firms Tech isn't really an industry... Amazon = Retail (and probably another 10-20% software and software services) Google = Advertising (and probably another 10-20% non advertising) Facebook = Advertising Microsoft = Software / Services (but very diversified) Also, companies like Bechtel and Saudi Aramco are not publicly traded but could be considered in the "largest" category. We just don't know what their market cap is because they're private.