The proposals include requiring marketable retail stock orders to be sent to auctions before they are executed, a new standard for brokers to show they get the best possible executions for client orders, and lower trading increments and access fees on exchanges, the SEC said. Opening up individual investor orders that can be immediately executed to competitive auctions could lead to "significantly" better prices for investors, the SEC said. Under current practice, retail brokers send most such orders to wholesale brokers, sometimes for a fee. "The competitive shortfall could be worth about $1.5 billion annually, compared with current practice — money that could go back into retail investors' pockets," said SEC Chair Gary Gensler. The changes, if adopted, would represent the biggest shakeup to stock market rules since the SEC introduced Regulation National Market System in 2005, which was aimed at modernizing and enhancing an increasingly fragmented and largely electronic marketplace.

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