Carl Icahn

Icahn buys undervalued companies with bad management. His thesis is consistently the same: there is enormous value being destroyed by entrenched executives who are more interested in keeping their jobs than returning value to shareholders.

He buys enough stock to force a confrontation. Sometimes management cleans itself up just from the threat of his involvement.

Sometimes he installs new people. Sometimes he forces a full sale of the company.

His version of value investing is more aggressive than Graham''s or Buffett''s. He doesn''t wait for the market to recognise value.

He forces the recognition. He is comfortable with conflict in a way most investors are not.

He sees confrontation with management as part of the job — not an unfortunate side effect of it.

Ken Griffin

Citadel is multi-strategy, meaning it runs many independent investment approaches simultaneously — equities, fixed income, commodities, macro, quantitative. Within each strategy, the approach is deeply research-driven and increasingly quantitative.

Griffin has built an organization that competes by having better data, better models, and better technology than rivals. He recruits aggressively from top universities and research institutions.

The edge is institutional, not personal — it is the collective intelligence of thousands of analysts and engineers working together, not one man's intuition.

Carl Icahn

He genuinely believes management teams destroy shareholder value through complacency, self-dealing, and entrenchment. He sees himself as a corrective force — not a vulture, but a mechanism by which markets hold management accountable.

Whether that''s how it looks from inside the companies he targets is a different question. His rules: buy when nobody else wants it, apply pressure to unlock the value, sell when the value is recognised.

Don''t get sentimental about positions. Don''t let management tell you the company is more complex than it looks.

Ken Griffin

Griffin believes that markets are competitions between the best-informed, best-equipped participants, and that winning over time requires relentless investment in research, technology, and talent. He has said that Citadel spends more on technology than most technology companies its size.

His philosophy is not about finding one great insight — it is about building systems that generate small edges consistently, at enormous scale, across thousands of trades and hundreds of strategies.

Carl Icahn

He concentrates. He uses leverage.

He''s comfortable with positions that make other investors deeply uncomfortable. He''s also comfortable being wrong in public — he''s had positions go spectacularly badly and he doesn''t hide from them.

His Hertz position went bankrupt during COVID. His Herbalife long was a very public, very watched position on the opposite side of Bill Ackman''s short.

He doesn''t bluff. When he says he''s going to fight, he fights.

Ken Griffin

Griffin is known for demanding risk management and being willing to cut positions aggressively when models signal danger. The 2008 loss of 55% is the exception that proves the rule — he survived it, refined the risk systems, and the firm has been significantly more resilient since.

He uses leverage extensively, but with a risk framework sophisticated enough that most of the firm's strategies are not correlated — when one book loses, another may gain. He is also known for being very hard on underperforming managers.

Carl Icahn

He lives in Sunny Isles Beach, Florida. He works ferociously hard and has done so into his late 80s.

He''s a hands-on manager — not someone who delegates. He famously said: "If you want a friend on Wall Street, get a dog." He has a Maltese named Tiger.

He''s been a prolific poker player and was once considered one of the best amateur players in New York. He remarried in 2012; his current wife is Gail Golden.

He''s given some money to charity but not at the scale of Buffett or Gates — he''s made no secret of prioritising returns over philanthropy.

Ken Griffin

Griffin is one of the most extravagant spenders of any investor on this list, and he does not hide it. He paid $238 million for a Manhattan penthouse, the most expensive home ever sold in the United States.

He bought a $122 million mansion in Palm Beach. He owns a Boeing 767 private jet.

He has donated over $1 billion to arts, education, and political causes — the University of Chicago's economics department is named after him following a $125 million gift. He is the largest individual donor in Illinois political history.

Carl Icahn

Apple. In 2013 he disclosed a $1.5 billion stake in Apple and published an open letter to Tim Cook urging a larger share buyback.

Apple eventually announced a significantly expanded buyback program. The stock rose.

Icahn made approximately $2 billion on the position. He didn''t have to engineer a hostile takeover — just making his involvement public was enough to move one of the largest companies in the world.

Ken Griffin

2022 is the defining year. While global markets were in freefall — the S&P 500 down 18%, bonds down dramatically, most hedge funds losing money — Citadel's Wellington fund returned approximately 38%.

The firm made $16 billion in profit for its investors in a single year, the most ever made by a hedge fund in one calendar year. The strategy worked because Citadel had positioned correctly for rising inflation and rising rates — a macro call that most funds missed entirely.

The $16 billion in 2022 alone exceeded the total profits of virtually any fund over its entire history.

Carl Icahn

TWA. He took over Trans World Airlines in 1985 using a leveraged buyout, extracted cash from the company to pay back the acquisition debt, and sold the valuable London routes to American Airlines for $445 million.

By the time he was done, TWA was a financially gutted airline. It went bankrupt in 1992, again in 1995, and was absorbed by American Airlines in 2001.

Icahn personally made hundreds of millions. The airline''s employees and creditors did not.

He''s defended his actions as legal. Legal and good for everyone are not always the same thing.

Ken Griffin

2008 is the dark chapter. Citadel's flagship funds lost approximately 55% during the financial crisis — not because of bad trading specifically, but because of a liquidity crisis.

Citadel held positions in illiquid securities that could not be sold without moving the market against them, and redemption pressure from investors compounded the problem. Griffin was forced to suspend redemptions — meaning investors who wanted to leave could not get their money out.

He spent months rebuilding. The firm survived, but the episode forced a fundamental redesign of Citadel's liquidity management and risk controls.

Carl Icahn

Carl Icahn grew up in Far Rockaway, Queens. His father was a failed opera singer who became a synagogue cantor.

Icahn studied philosophy at Princeton — graduated 1957 — then enrolled in NYU School of Medicine before dropping out after two years to join the army. He became a stockbroker at Dreyfus & Co.

in 1961, saved $400,000, and bought a seat on the New York Stock Exchange in 1968.

He spent the early years running option arbitrage — finding and exploiting small mispricings. He was very good at it.

In the late 1970s he pivoted to a bigger game: buying large stakes in undervalued companies and forcing management changes. His first major target was Tappan Company in 1979.

By the mid-1980s he was feared by corporate boards across America. Oliver Stone''s Gordon Gekko in Wall Street is directly based on the era Icahn created.

Ken Griffin

Griffin grew up in Boca Raton, Florida, and showed early signs of being extremely competitive and extremely interested in markets. He enrolled at Harvard in 1986 and almost immediately started trading — he installed a satellite dish on the roof of his dorm to get live stock data, and began running convertible bond arbitrage strategies with money raised from family.

By the time he graduated in 1989, he had been profitable enough that a hedge fund manager named Frank Meyer had given him $1 million to manage.

He launched Citadel LLC in 1990 at age 22 with $4.6 million. The name came from the idea of building something fortified, defensible, and hard to breach.

He spent the 1990s building out quantitative infrastructure, recruiting mathematicians and engineers rather than traditional traders, and expanding into multiple strategies. By the 2000s, Citadel was one of the most feared names in hedge funds.

The 2008 financial crisis hit the firm hard — the flagship funds lost about 55% — but Griffin did not close. He survived, rebuilt, and came out stronger.

Carl Icahn

Icahn Enterprises is his publicly traded holding company. He''s been chairman since 1987.

Some of his most famous investments: TWA, which he took over in 1985, stripped its most valuable routes to pay back the debt used to acquire it, and left financially hollowed out — it went bankrupt twice after his tenure. Texaco, where he forced a settlement that paid shareholders.

Apple, where he took a $1.5 billion position in 2013 and published an open letter to Tim Cook demanding a larger share buyback. Apple eventually expanded the buyback.

The stock rose. Icahn made roughly $2 billion on the position without engineering a hostile takeover — the threat of his involvement was enough to move a $500 billion company.

He''s also had notable losses. Hertz went bankrupt during COVID while he held a large position.

He lost hundreds of millions.

Ken Griffin

Citadel LLC is the hedge fund business, managing approximately $58 billion. It runs multiple strategies across equities, fixed income, macro, and credit.

Its flagship Wellington and Kensington funds have produced extraordinary long-term returns — compounding at roughly 19% annually since inception. The firm has thousands of employees across multiple continents and is considered one of the most technologically sophisticated investment firms in the world.

Citadel Securities is a separate but equally important business. It is one of the largest market makers in US equities, handling approximately 25–30% of all US retail equity order flow.

When someone uses Robinhood or TD Ameritrade to buy a stock, there is a meaningful chance Citadel Securities is on the other side of that trade. This business is enormously profitable and is what made Griffin one of the wealthiest people in finance.

Carl Icahn

Princeton University, BA in Philosophy, 1957. NYU School of Medicine, dropped out after two years.

He''s credited Princeton''s philosophy training with teaching him to question conventional wisdom — which shows up directly in how he argues with corporate boards.

Ken Griffin

Harvard University, BA in Economics, 1989. He arrived already interested in markets and left already running a fund.

He has donated hundreds of millions to Harvard and to the field of economics broadly — the Griffin Graduate School of Arts and Sciences at Harvard was named in his honor following a $300 million gift, the largest in Harvard's history.