Spilker joined Apollo as president in December 2010 after retiring from Goldman Sachs, where he spent 20 years and left as co-head of the bank's investment management division.
"Marc leaves a firm that has fulfilled the vision it set for itself to become a successful public company and to put in place the infrastructure and resources it requires," said Leon Black, Apollo's co-founder, chairman and chief executive.
Apollo's statement on Thursday made no mention of any plans to replace Spilker.
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The company, which has a market value of about $5 billion, went public in March 2011.
Spilker, 49, graduated with degree in economics from the Wharton School of the University of Pennsylvania.
Apollo, whose biggest competitors include KKR and Blackstone Group, had assets under management of about $161 billion at the end of 2013.
Apollo's shares closed at $32.54 on Wednesday on the New York Stock Exchange. (Click here to see what the stock is doing now)