Wall Street billionaire Leon Black expressed remorse for his personal business and philanthropic relationship with Jeffrey Epstein on Monday in a letter sent to investors and obtained by Axios.

Driving the news: Black's letter follows a bombshell New York Times report that reveals that ties between Black, founder and CEO of Apollo Global Management, and Epstein were deeper than previously disclosed, including upwards of $75 million changing hands.

In the letter to limited partners in Apollo funds, Black reiterated past statements that Epstein was never involved in Apollo business, and that he engaged Epstein in "estate planning, tax, and philanthropic endeavors."

• Black also wrote that his family was with him during a visit to Epstein's infamous island estate, and that he occasionally met at Epstein's townhouse because Epstein didn't maintain a separate office.
• He also said he will cooperate with all legal inquiries into Epstein.

Read the letter.