Founder and CEO, Citadel
Ken Griffin started trading convertible bonds from his Harvard dorm room and built that into Citadel, one of the most profitable hedge funds ever. Separately, Citadel Securities sits on the other side of a substantial share of all US equity trades. That gives Griffin a view of the market almost nobody else on this list has: that of the plumbing itself.
Where most investors talk about what they are buying, Griffin talks about how the market works: liquidity, spreads, the role of market makers and the consequences of regulation. When he warns that market structure is becoming fragile, that is a different kind of signal from a price forecast.
Starts trading convertible bonds as a Harvard student, with a satellite dish on his dorm roof.
Founds Citadel with capital from an investor who had noticed his results.
Founds Citadel Securities, which grows into one of the world's largest market makers.
Citadel loses more than half its value in the crisis but survives and fully recovers.
Lands at the centre of the public market structure debate during the meme stock rally.
Moves Citadel's headquarters from Chicago to Miami.
Quotes still to be added. Only add them together with a source and a date.
Updated: 2026-07-23
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