It is understood Rees resigned and is set to go back into practice. According to a report from Sky News, he is set to join US law firm King & Spalding as a partner.
The FRC confirmed his resignation but has yet to provide a timetable for recruiting his replacement.
During his time at the accountancy watchdog he was involved in several misconduct cases that resulted in record penalties for big firms and their partners including Deloitte and its work on both Aero Inventory Plc and MG Rover. Grant Thornton was fined £2.27m over AssetCo and, more recently, PwC was fined £5.1m for its audit of RSM Tenon.
Earlier this year, the FRC was forced to launch an internal investigation into one of its members, barrister Stephen Wooler, after he leaked a confidential judgement on PwC to the press ahead of the official hearing.