Leon Black, the billionaire co-founder of private equity giant Apollo Global Management, has quit citing "relentless public attention and media scrutiny" over his ties to Jeffrey Epstein.
Mr Black had already said earlier this year that he would step down as chief executive on or before July but was to have stayed on as chairman - a role he is now also relinquishing with immediate effect.
It comes after an independent review of Mr Black's links to Epstein, the financier who died in jail in 2019 while awaiting trial on sex trafficking charges.
The review, by law firm Dechert, revealed in January that Mr Black had paid Epstein $158m for advice on tax and estate planning and related services between 2012 and 2017.
It cleared Mr Black of any wrongdoing.
In a letter to Apollo's board of directors, he said that "the last weeks and months have been deeply trying for me and my family".
He added: "The relentless public attention and media scrutiny concerning my relationship with Jeffrey Epstein - even though the exhaustive Dechert report concluded there was no evidence of wrongdoing on my part - have taken a toll on my health."
Mr Black said he wished "to take some time away from the public spotlight that comes with my daily involvement with this great public company".
The businessman, who co-founded New York-based Apollo 31 years ago and turned it into one of the world's largest private equity groups, is worth $8.5bn according to Forbes.
Apollo said on Monday that co-founder Marc Rowan has now formally assumed the role of chief executive and that former Securities and Exchange Commission (SEC) boss Jay Clayton, already on the company's board, has been named as chairman.
Mr Black said his decision came after the company recently announcing an $11bn tie-up with annuities provider Athene Holding, and with quarterly earnings on track to beat analysts' forecasts.
"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.
"I believe strongly that Apollo's best days lie ahead. I intend to remain Apollo's largest shareholder, and strongest supporter."
Founded in 1990, Apollo now has offices around the world and manages assets totalling more than $450bn.