The U.S. Securities and Exchange Commission's chief economist, James Overdahl, will be leaving at the end of the month, he said on Tuesday.
Overdahl, who was in charge of the SEC's office of economic analysis before it was merged with another office, will be joining National Economic Research Associates.
Before joining the SEC, Overdahl was the chief economist at another U.S. market regulator, the Commodity Futures Trading Commission.
Overdahl will be leaving after the SEC passed controversial rules to restrict short selling in a company's stock if it fell precipitously.
He joined the SEC in July 2007 after the agency's Office of Economic Analysis helped provide the regulator with analyses that concluded that a Depression-era short sale curb called the uptick rule was ineffective in modern markets.
The SEC's office of economic analysis was merged with the SEC's office of risk assessment to create the division of risk, strategy and financial innovation.
(Reporting by Rachelle Younglai; Editing by Richard Chang)