Apollo Global Management Inc. /zigman2/quotes/203829595/composite APO +0.98% said Monday that co-Founder Marc Rowan has assumed the role of chief executive, replacing co-Founder Leon Black who is stepping down as part of the succession plan first announced in January. Black said he would surrender the role before his 70th birthday on July 31. The private-equity firm said Jay Clayton, former chairman of the Securities and Exchange Commission, will become non-executive chair of the board. Richard Emerson, current president of Pendral Capital, and Dr. Kerry Murphy Healey, inaugural president of the Milken Center for Advancing the American Dream in Washington, DC, will become independent board members with immediate effect. "In the last few months, not only did we announce a transformative merger with Athene, but also expect to report that our first quarter earnings will exceed analyst consensus in all relevant measures and that the first quarter fundraising is trending towards the high end of our $15-20b annual range," Black said in a statement. "I thus view this as the ideal moment to step back and focus on my family, my wife Debra's and my health issues, and my many other interests." Black first said he would step down in January, after an independent review revealed larger-than-expected payments -- $158 million in all -- to disgraced financier Jeffrey Epstein that it nevertheless deemed justified, as the Wall Street Journal reported at the time. Black "believed, and witnesses generally agreed, that Epstein provided advice that conferred more than $1 billion and as much as $2 billion or more" in tax savings, the report stated. Apollo shares were down 0.2% premarket, but have gained 76% in the last 12 months, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.01% has gained 70%.