Jay Clayton was sworn in as chairman of the Securities and Exchange Commission on Thursday afternoon.
The private equity lawyer was nominated by President Trump to lead the agency, and confirmed by the Senate on Wednesday.
Before joining the SEC Clayton was a partner at Sullivan & Cromwell, where his clients including Oaktree, Och-Ziff and Goldman Sachs.
He will be recused from cases involving former clients or those of Sullivan & Cromwell for two years under ethics rules. He is also obliged to divest his holdings in public and private equity funds within 90 days of being sworn in.
His financial disclosure form showed he has interests in 54 private equity funds including Centerbridge Capital Partners III, Thoma Brava Discover Fund and Hellman & Friedman Capital Partners VIII.