Last year, NYSE Euronext, which operates the New York Stock Exchange, agreed to pay $5 million in the first fine ever levied against an exchange by the securities regulator. NYSE Euronext, which didn’t admit or deny wrongdoing, was accused of favoring certain customers by giving them trading information ahead of others through proprietary data feeds. In May, the SEC fined Nasdaq $10 million for poor systems controls and decision-making tied to its handling of last year’s Facebook Inc. public offering, which left Wall Street firms with about $500 million in losses. Nasdaq neither admitted nor denied wrongdoing in the matter.
SEC enforcement officials have also been investigating whether some stock exchanges have provided high-speed traders “order types”—commands that tell an exchange how to handle an order—that can give the traders advantages over other investors.