The U.S. Securities and Exchange Commission said this week that hackers managed to infiltrate one of its systems last year, something that likely facilitated insider trading.

Wall Street-savvy hackers are behind a data breach that involves a who’s-who of New York City legal firms. Federal investigators are looking into the breach that included Cravath Swaine & Moore LLP and Weil Gotshal & Manges LLP, both high-profile New York-based law firms. Cravath Swaine & Moore said told Threatpost its computer networks were infiltrated...