The Financial Industry Regulatory Authority's head of enforcement, Susan Merrill, is leaving her job, according to published reports.

The Wall Street Journal reported late Wednesday that Merrill, 53, will step down from the job she's held since the National Association of Securities Dealers and the regulatory arm of the New York Stock Exchange merged in 2007 to create FINRA. Before that, Merrill joined the NYSE's regulatory division in 2004.

FINRA's disciplinary actions and fines against the brokerage industry have declined during Merrill's tenure as the organization's top enforcement watchdog, the Wall Street Journal reported.

Among the successes: FINRA has brought a number of auction-rate securities cases against Wall Street firms. On the other hand, according to the report, the number of disciplinary actions filed by FINRA has declined 17% between 2005 and 2009.