Heading into 2018, corporate leaders braced for public backlash: For the first time, thousands of publicly traded U.S. companies would be required by the U.S. Securities and Exchange Commission to disclose how much their chief executive officers made compared with their median workers.

Executive compensation has soared about 1,000 percent since 1978, while real wages for most Americans are up about 11 percent, according to an Aug. 16 report from the Economic Policy Institute. Putting a number to that...