​An analysis from the Wall Street Journal found that, in the wake of the Tax Cuts and Jobs Act, the average effective corporate tax rate among S&P 500 companies fell from 25.5 to 19.8 percent over two years, attributed largely to a few big companies no longer paying the top rate. Prior to the new tax law, there were 143 companies in the S&P 500 reported having an effective global tax rate over 32 percent in the first quarter; since then, that number has plunged to 28. Meanwhile, the number of S&P 500 firms with a global effective tax rate of 12 percent or below has increased from 93 to 119 in the same time period.

The new tax law has resulted in, overall, less variation among companies in what they pay in taxes. While 58.4 percent of S&P 500 companies are paying fewer taxes, 16.7 percent are actually paying more (the remainder are holding steady, with rates similar to what they were prior to the overhaul). The higher tax for some companies was due to factors such as the GILTI tax, which functions as a sort of global minimum tax in order to discourage the use of foreign subsidiaries to avoid U.S. taxes.