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.

The access fee caps help to ensure that market participants have fair access to the best displayed prices, the SEC said in a fact sheet.

The price increments at which thousands of stocks and ETFs are quoted look set for an overhaul Wednesday, when the US Securities and Exchange Commission votes on final rules to reduce them to less than 1 cent.

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.