John Hack joined Apollo in 2023 as Chief Operating Officer of Engineering. Prior to that, he was a Managing Director and Chief Operating Officer of Electronic Trading Engineering at Citadel from 2020 to 2023. From 2008 to 2020, John held multiple global technical and operational leadership roles at D. E. Shaw and its spin-off, Arcesium. He spent his early career in consulting and software development at AIG and Random Walk Computing, remaining with Random Walk following its acquisition by Accenture.

John serves on the board of Play Rugby USA, a nonprofit focused on youth development through sport in Harlem and the Bronx. He graduated from Duke University with a BSE in Electrical and Computer Engineering and a second major in Computer Science.