The Republican tax plan could see US retail investors dump stock as they lose their ability to choose which shares to sell to reduce a position.
Asset managers have lobbied to be exempt from the requirement to sell shares on the “first in, first out” (Fifo) basis, the Wall Street Journal reports.
However, retail investors would lose the ability to reduce their capital gains tax bill by selling specific shares based on their purchase date.
The changes for retail investors could raise $2.4bn over the next decade.
The Dow Jones soared when the tax reform bill passed through the US Senate earlier this month.