Wall Street's top regulator on Wednesday unveiled rules allowing stock markets to price 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.

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.

Stocks are currently priced in increments of one-cent. But a move by the SEC could lower transaction costs for consumers.

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

The U.S. Securities and Exchange Commission is poised to approve a rule that will allow exchanges to quote sub-penny prices as it seeks to foster competition, according to a media report. The Regulation NMS: Minimum Pricing is part of a broader set of regulations that proposes to overhaul U.