American options trader.
Co-founder and managing director of Susquehanna International Group (SIG), a privately held trading and technology firm.
In 2001, Yass joined the executive advisory council of the Cato Institute, a DC-based American libertarian think tank. It was co-founded in 1977 by Ed Crane, Charles Koch, and Murray Rothbard.
Jeff Yass - Wikipedia
"Beating the Odds – Susquehanna International – Jeff Yass" - Philly Mag (2009)
Cato Institute - Wikipedia