The retail liquidity programme, set to launch next month, will offer investors Nyse and Nasdaq listed stock quotes in increments of less than a penny, enabling them to get better prices.

This sub-penny pricing on exchanges is usually prohibited under SEC rules but not to other trading venues, which has meant many retail investors have turned to dark pools.

The SEC says the move - which is expected to be copied by other exchanges - will help promote competition but both the Securities Industry and Financial Markets Association and the Securities Traders Association have objected.

Joseph Mecane, EVP, Nyse Euronext, says: "Providing price improvement for retail orders within an exchange environment affords individual investors new economic incentives and ensures greater transparency, liquidity and competition throughout the US cash equities marketplace."