On Thursday, the S&P 500 closed above 5,700 for the first time, while the Dow jumped above the 42,000 level. Here's what CNBC is watching going into Friday.

"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 "The one-penny minimum has become outdated.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."

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.

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.

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.