(Bloomberg) -- The U.S. Securities and Exchange Commission approved a rule Wednesday requiring companies to reveal the pay gap between the chief executive officer and their typical worker, handing a new weapon to groups protesting rising income inequality.

The commission voted 3 to 2 to mandate the disclosure. The agency had delayed progress on the rule for years, with SEC Chair Mary Jo White facing attacks from unions and Democratic lawmakers in recent months for failing to get it done.

The disclosure is required under the 2010 Dodd-Frank Act, which hasn’t stopped it from splintering the five-member commission. Republican commissioners and business groups argue it’s meant to embarrass CEOs and won’t be useful to investors.