Bill Ackman

Ackman is a concentrated, long-hold, activist investor. He typically owns 5–10 positions at a time — sometimes fewer.

Each one involves exhaustive research. If he's buying, he has usually already built a 100-slide deck explaining exactly what's wrong with the company and exactly what needs to change to fix it.

His style is the opposite of index investing. He wants a controlling voice at the table.

He wants to talk to the CEO. He wants the board to change.

That's the "activist" part — he's not just buying a stock and hoping it goes up. He's buying it with a plan to force the thing that will make it go up.

The strategy works until it doesn't. When the thesis is right, he wins massively.

When the thesis is wrong and he's also very public about it, the losses are spectacular.

Peter Lynch

Lynch invented the phrase "tenbagger" — a stock that returns ten times your money. He was specifically looking for companies that could do that.

His method was deceptively simple: invest in what you know. Not what you know about macroeconomics or interest rates — what you know about everyday life.

What stores are you shopping at? What products are your kids obsessed with?

What new thing are you using that feels like it could be everywhere in five years? If you're noticing a company before Wall Street analysts have caught on, you have a real edge.

He categorized stocks into six types: slow growers (stable, boring), stalwarts (big companies, modest returns), fast growers (small and aggressive — where the tenbaggers live), cyclicals (tied to economic cycles), turnarounds (troubled companies that might recover), and asset plays (companies with hidden value the market hasn't priced in). His genius was applying rigorous fundamental analysis to companies most Wall Street analysts dismissed as too small or too mundane to bother with.

Bill Ackman

Ackman's core belief is that markets frequently misprice assets when the story around them is either too negative or too complicated. He looks for businesses he can understand deeply, with a gap between what the market thinks they're worth and what he thinks they're worth.

He's talked extensively about asymmetric bets — situations where you can be wrong and lose a small amount, but right and make a lot. He believes activist investing works because most company boards are too comfortable and most CEOs have too little accountability.

He thinks public pressure, when backed by real analysis, is a legitimate tool for creating value. Whether that makes him a hero or a villain depends on which company you ask.

Peter Lynch

He believed the average person has a real edge over professional fund managers — specifically the access to everyday life that analysts in offices don't have. You know which stores are packed on Saturday afternoon.

You know which new products your kids are obsessed with. Wall Street analysts often don't.

His most repeated principle: invest in what you know. His second: loving a company's product is not enough on its own — you still have to understand the fundamentals.

Third: stomach matters more than brain in investing. The biggest thing separating successful investors from unsuccessful ones isn't intelligence — it's the ability to stay calm when the market drops 20 percent and everything feels like it's ending.

Bill Ackman

Ackman runs highly concentrated books and uses leverage. That's the opposite of conservative.

He'll put 20–30% of the fund in a single position if he believes in it. He also uses options and credit derivatives — his March 2020 COVID hedge was built using credit default swaps, instruments most retail investors have never heard of.

He famously described his risk approach as: "I only invest when the downside is zero and the upside is unlimited" — which sounds great until you lose $4 billion on one trade. The honest version is: he's a high-conviction investor with a high tolerance for pain on the way to being right.

Peter Lynch

Lynch ran a very diversified portfolio — sometimes over 1,000 positions — which cuts against the concentration gospel of Buffett and Munger. He justified it simply: if you find enough genuinely great small companies, you don't need to pick just one.

Some will fail. The tenbaggers more than compensate.

He wasn't reckless — he did detailed fundamental research on every holding. But he was comfortable owning things that looked messy or unfamiliar on the surface if the numbers told a better story.

His rule was that you should never own more companies than you can actually keep track of. He could track hundreds because researching them was his full-time job.

For everyone else the honest number is far smaller, and he said so.

Bill Ackman

Ackman has a taste for the finer things and doesn't pretend otherwise. He owns a large Manhattan apartment, he's been photographed at high-end charity events, and his social circle overlaps with New York media, finance, and political elite.

He and his second wife, Neri Oxman, have a high public profile — she's a former MIT professor and design pioneer. He is a Harvard alumnus, twice over, and gave to the school for years, though the relationship became famously strained in 2023 when he led a very public campaign against Harvard's president over campus antisemitism, ultimately contributing to her resignation.

He is not a guy who stays quiet about anything.

Peter Lynch

After retiring from Magellan in 1990, Lynch has spent most of his time on philanthropy. He and his wife Carolyn donated tens of millions to education through the Lynch Foundation, focusing on Catholic education and scholarship programs in Massachusetts.

He lives quietly for someone worth hundreds of millions. He speaks at Fidelity events occasionally, plays golf, and is generally not seeking attention.

He has said that the best decision he ever made was retiring at 46 — that no amount of money is worth missing your kids grow up.

Bill Ackman

The COVID hedge in March 2020 is the one. As markets started selling off in late February, Ackman quietly spent $27 million buying credit default swaps — basically insurance on corporate bonds defaulting if the economy collapsed.

He then went on CNBC on March 18, 2020, visibly emotional, and said "hell is coming." The market kept dropping. Three weeks later, he unwound the trade.

The $27 million had turned into $2.6 billion. That's roughly a 100x return in under a month.

He used the proceeds to buy stocks at the market bottom. He then made another fortune as markets recovered.

The whole sequence — hedge, cry on TV, buy the dip, profit — is one of the more remarkable individual trade sequences in recent hedge fund history.

Peter Lynch

Fannie Mae. Lynch bought it heavily in the mid-1980s when almost nobody wanted it.

It was a housing finance company drowning in problem mortgages. Lynch dug into the fundamentals and decided the problems were fixable and the underlying business was genuinely valuable.

He was right. The stock went from roughly $2 to $40.

That single position generated hundreds of millions for the fund. His Chrysler bet was similar — he bought heavily when the company was a bankruptcy rumor and almost no one else would touch it.

Both worked because Lynch was willing to do the research on things everyone else had already decided were too ugly to look at.

Bill Ackman

The Valeant Pharmaceuticals disaster is the one. Ackman built a massive position in Valeant starting in 2015, eventually owning about $4 billion worth of shares.

His thesis was that Valeant's model — aggressively raising drug prices and cutting R&D — was brilliant. Congress, journalists, and eventually the SEC had a different view.

The stock collapsed from $260 to under $10. Ackman spent months publicly defending the position, appearing on CNBC repeatedly to explain why it would recover.

It didn't. He finally sold in 2017 at a loss of approximately $4 billion.

It's the most expensive public loss in hedge fund activism history. The lesson he's cited: don't get emotionally attached to a position, and be faster to recognize when the fundamental thesis has broken.

Peter Lynch

Selling great companies too soon. He got into Walmart early and sold too soon.

He did the same with several other retailers that went on to become enormous. By his own account, his biggest mistake pattern was taking profits on genuine multi-decade compounders before they had compounded enough.

He also acknowledged that managing a $14 billion fund was fundamentally different from managing $18 million. The sheer size limited which companies he could meaningfully invest in — you can't move the needle on a $14 billion fund by buying a $50 million company.

He burned himself out keeping up with over a thousand positions. He retired at 46.

He's said he doesn't regret it.

Bill Ackman

Bill Ackman grew up in Chappaqua, New York, the son of a real estate finance chairman. He was a history major at Harvard — class of 1988 — then went straight to Harvard Business School.

His first venture was Gotham Partners, a real estate and value investing fund he started in 1992 with a Harvard classmate. It was a disaster.

The fund made concentrated bets on illiquid real estate and had to be wound down by 2003 under serious investor pressure and SEC scrutiny.

He didn't quit. In 2004 he launched Pershing Square Capital Management, this time with a clearer focus: take large stakes in companies, go public with his thesis, and use activist pressure to force management changes.

The approach worked. His reputation was built on detailed, public investment presentations — sometimes running 100+ slides — that became must-reads on Wall Street.

He turned activist investing into something that felt more like journalism than finance: research a company, find what's broken, publish everything, and bet heavily on being right.

Peter Lynch

Peter Lynch grew up in Newton, Massachusetts. His father died when Lynch was 10, and his mother had to work to keep the family going.

Lynch caddied at the Brae Burn Country Club to help out. One of his regular clients was D.

George Sullivan, president of Fidelity Investments. Sullivan eventually offered Lynch a summer job at Fidelity — the kind of break you earn by showing up and doing the work.

Lynch studied history, psychology, and philosophy at Boston College — not finance — and said later that was probably an advantage. Too many finance students learn to look at spreadsheets and miss the obvious things happening in front of them.

He got an MBA from the Wharton School, joined Fidelity full-time in 1969, and took over the Magellan Fund in 1977. At the time, Magellan had $18 million in assets and was closed to new investors.

When Lynch retired at 46 in 1990, it had $14 billion and was the largest actively managed mutual fund in the world. He beat the S&P 500 in 11 of his 13 years managing it.

He's been a vice chairman at Fidelity in an advisory capacity ever since.

Bill Ackman

Pershing Square Capital Management is his flagship hedge fund, managing around $16 billion. His most famous public positions have included Canadian Pacific Railway, where he pushed successfully for a new CEO and a turnaround that made Pershing Square hundreds of millions.

He held a massive position in Valeant Pharmaceuticals from 2015 to 2017 — which will come up again. He took a huge bet on General Growth Properties during the 2008 financial crisis when no one else would touch it.

That one returned over $1 billion.

He has also done business on the other side: Pershing Square Holdings is his publicly listed vehicle on Euronext Amsterdam, which lets retail investors access his fund — unusual for a hedge fund of this size. He's been a major Burger King and Restaurant Brands International investor, and he backed Fannie Mae and Freddie Mac preferred shares in a long-running legal battle with the government.

Peter Lynch

His entire professional life ran through Fidelity Investments. He managed the Magellan Fund from 1977 to 1990 — 13 years of sustained outperformance that has never been matched at that scale.

His major holdings during that run included Fannie Mae, which he rode from $2 to $40. Chrysler, which he bought near bankruptcy.

And various retailers that nobody on Wall Street wanted to touch.

He was famous for finding companies in everyday life before analysts noticed them. He found Dunkin' Donuts because his wife liked the coffee.

He investigated L'eggs pantyhose after his wife bought them at a grocery store. He'd walk through a shopping mall and watch which stores were packed and which were empty — and then go home and read the financials to see if the story held up.

Bill Ackman

Harvard College, BA in History, 1988. Harvard Business School, MBA, 1992.

He's been a major Harvard donor — and major Harvard critic — throughout his career. The irony of his most public fight being with his own alma mater was not lost on anyone.

Peter Lynch

Boston College, class of 1965 — history, psychology, philosophy. Wharton School of Business, MBA.

He's on record saying studying history at Boston College was more useful for investing than anything he learned at Wharton. The historical pattern recognition, the ability to contextualize events — that showed up in how he thought about cycles and companies.