"This will lower costs for investors as well as improve liquidity, competition and price efficiency in the markets," SEC Chair Gary Gensler said in a statement ahead of the vote. "The one-penny minimum has become outdated. It's too wide in many stocks."

The U.S. Securities and Exchange Commission will vote on a proposed amendment to change the minimum pricing increment for most stocks.

US regulators dumped long-standing penny limits on share trading prices and cut the fees exchanges can charge their users in new equity market rules that nonetheless ended far short of more radical initial plans.

Wall Street's top regulator on Wednesday unanimously voted to allow stock exchanges to price many shares in increments of half a penny, rather than the current minimum size of 1 cent, aiming to promote more competitive pricing and reduce investor costs on the $55 trillion U.