Our tax system is based on the concept of “realization.” Individuals are not taxed until they actually sell property and realize their gains. But this system makes less sense for the publicly traded stocks of the superwealthy. A drastic change is necessary to fix this fundamental flaw in our tax system and finally require people like Warren E. Buffett, Mr. Ellison and others to pay at least a little income tax on their unsold shares. The fix is called mark-to-market taxation.