Warren Buffett

Buffett's approach is simple to describe and almost impossible to copy. He buys great businesses at fair prices and then just...

holds them. Forever.

He calls it "buy and hold" but that undersells it — he means hold until the sun burns out. He looks for companies with a real unfair advantage over competitors.

Something that protects them from being wiped out. He calls it a "moat" — like the water around a castle.

Think Coca-Cola. Everyone knows it.

Nobody can replicate it. He puts a LOT of money into a small number of bets — usually his top five holdings make up over 70% of everything.

Most fund managers would have a panic attack at that level of concentration. Buffett calls it being convicted.

His old mentor Graham taught him to hunt for cheap, beaten-down companies and flip them fast. Charlie Munger, his business partner for 45+ years, talked him out of that.

Munger said: just buy the best businesses you can find and never sell. Buffett admits that shift made him hundreds of billions of dollars.

Jim Simons

Renaissance is a pure quantitative shop. The approach is based on finding statistical patterns in historical price data and other measurable signals across thousands of financial instruments — stocks, bonds, commodities, currencies — and trading them at high frequency and scale.

The specific models are among the most closely guarded secrets in finance. Renaissance does not discuss its methods publicly.

Employees sign comprehensive non-disclosure agreements. What is known: the edge is in the data, the models, and the execution infrastructure — not in any human's judgment about individual companies.

Warren Buffett

Rule No. 1: Never lose money.

Rule No. 2: Never forget Rule No.

1. Buy businesses, not stocks — the distinction matters more than most investors realize.

Let compounding do the heavy lifting and get out of its way. Never use debt to invest.

Be fearful when others are greedy, greedy when others are fearful. Time in the market destroys timing the market in every long enough data set.

For most people, a low-cost S&P 500 index fund will outperform almost any active strategy, including most professional money managers — including, he's said, what most of his estate will go into after he's gone.

Jim Simons

Simons believed that markets contain statistical signals that repeat because human behavior repeats. He rejected the Efficient Market Hypothesis not on philosophical grounds but on empirical ones: the data showed patterns that persisted.

His philosophy was that intuition and narrative are unreliable — models trained on evidence are more consistent. He also believed that the best people to find these patterns were scientists and mathematicians, not finance people, because scientists are trained to find truth in data rather than to construct convincing stories.

Warren Buffett

Buffett's whole thing is: do so much homework that the risk basically disappears. He doesn't diversify across 500 stocks to protect himself — he researches 10 companies so deeply that he's more confident about those 10 than most people are about anything.

He never borrows money to invest. Ever.

He keeps a mountain of cash at Berkshire — over $100 billion sitting around doing nothing — specifically so he can swoop in when everyone else is panicking and selling cheap. He once called derivatives "financial weapons of mass destruction" back in 2002.

Wall Street laughed. Then 2008 happened and Wall Street stopped laughing.

He doesn't predict where the stock market is going. He predicts whether a business will still be dominant in 20 years.

That's it.

Jim Simons

Renaissance uses significant leverage within the Medallion Fund — reportedly up to 20:1 in some strategies. The risk management is entirely model-driven.

Positions are sized according to statistical confidence intervals, correlation analysis, and liquidity constraints. Human intuition plays no role.

The strategy has experienced sharp drawdowns — Medallion lost approximately 6% in August 2007 during the "quant quake" when many quantitative funds deleveraged simultaneously, causing crowded positions to move violently. The fund recovered within months.

Warren Buffett

Despite a $120B net worth, Buffett still lives in the same gray stucco house in Omaha he bought in 1958 for $31,500. He drives himself to work.

Breakfast is McDonald's — he orders based on his mood: $2.61, $2.95, or $3.17. He plays bridge obsessively, often online with Bill Gates.

He drinks multiple Cokes a day (Berkshire owns a large stake in Coca-Cola; coincidence is left as an exercise to the reader). He has pledged to give away more than 99% of his wealth, primarily to the Bill & Melinda Gates Foundation and his children's foundations.

He takes a $100,000 annual salary from Berkshire. He does not own a smartphone.

Jim Simons

Simons was notably generous in a quiet way for most of his career, then became one of the largest philanthropists in American history. The Simons Foundation, which he ran with his wife Marilyn, donated billions to mathematics research, autism research, and scientific education.

He funded the Math for America program to train mathematics teachers. He also donated hundreds of millions to Stony Brook University, where he had taught.

He smoked cigarettes openly — a trademark noted in virtually every profile written about him.

Warren Buffett

Apple. Berkshire started buying Apple in 2016 — late by any tech investor's standard, from a man who spent decades insisting he didn't understand technology.

By 2023, the position had grown to over $170 billion, returning more than 800%. Buffett called it the best business he'd ever seen and admitted he should have bought it earlier.

Honorable mention: American Express in 1963 during the Great Salad Oil Scandal, when he put 40% of the Buffett Partnership into AmEx at distressed prices while the rest of Wall Street was running away.

Jim Simons

Thirty-five years of Medallion Fund returns is the win, and calling it "the biggest win" undersells it. From 1988 to 2023, the fund never had a losing year.

Its worst calendar year was approximately flat. In 2000, when the dot-com bubble burst and most funds lost heavily, Medallion returned 98.5%.

In 2008, during the global financial crisis, it returned 80%. In 2020, a year of historic market volatility, it returned approximately 76%.

It did not just beat the market — it beat the market in conditions specifically designed to destroy other strategies. Simons and his early partners became multi-billionaires through the fund's returns.

The people who invested in it — Renaissance employees — also became extraordinarily wealthy.

Warren Buffett

Buying Berkshire Hathaway. He bought it in 1962 as a cigar butt — a cheap, dying textile company — and then kept it instead of winding it down into a clean insurance holding company.

The C-corp structure meant decades of tax drag. He has estimated this single mistake — triggered partly by spite after the owner tried to lowball him on a buyout — cost Berkshire and its shareholders roughly $200 billion over 50 years.

He also admits missing Google and Amazon, both of which he understood well enough to buy and simply didn't.

Jim Simons

The external funds — RIEF and RIDA — represent the most honest version of a limitation rather than a mistake. When Simons opened Renaissance to outside investors through these vehicles, performance was strong but meaningfully below Medallion.

The gap between the internal and external fund performance is estimated at roughly 30–40 percentage points per year. This suggests that the strategy that powers Medallion cannot be scaled to the size required by institutional capital without degrading returns — a fundamental constraint that no amount of genius has fully overcome.

Warren Buffett

Warren Buffett was born in Omaha, Nebraska in 1930. He bought his first stock at age 11 — three shares of a company called Cities Service.

He paid $114. He was eleven.

By 14, he owned a 40-acre farm and had filed his first tax return. He applied to Harvard Business School and got rejected.

Best thing that ever happened to him, honestly. He ended up at Columbia instead, where he met Benjamin Graham — the guy who basically invented the idea of buying undervalued stocks.

After graduating in 1951, Buffett started his own investment partnership in Omaha with $105,000 from family and friends. He turned that into something much bigger, compounding at around 30% per year for over a decade.

Then in 1969, he shut it down and quietly took over a dying Massachusetts textile company he had bought partly out of spite. That company was Berkshire Hathaway.

What happened next is the greatest investing run in history — and it started with a grudge.

Jim Simons

Simons was born in Newton, Massachusetts in 1938. He showed mathematical gifts early and earned his PhD in mathematics from the University of California, Berkeley at age 23.

He spent several years doing work for the US government — specifically codebreaking at the Institute for Defense Analyses during the Cold War — before returning to academia. He chaired the mathematics department at Stony Brook University from 1968 to 1978 and produced research in differential geometry that became foundational.

The Chern-Simons theory, developed with Shiing-Shen Chern, remains important in both mathematics and theoretical physics.

He left academia in 1978 to trade currencies, initially unsuccessfully. In 1982 he founded Renaissance Technologies, a quantitative trading firm.

He spent the next decade building something genuinely new: a team of mathematicians, physicists, and computer scientists — deliberately not hiring economists or traditional finance people — who used pattern recognition and statistical models to trade financial markets. By the early 1990s the Medallion Fund's returns had become extraordinary.

By the 2000s, Renaissance was the most profitable firm per employee in finance.

Warren Buffett

His main vehicle is Berkshire Hathaway — a company he took over in 1965 when it was a dying textile mill. He basically gutted the textile business and turned the whole thing into a giant money machine that owns other businesses.

Today it's one of the most valuable companies on earth. On the stock side, his biggest bet is Apple — worth over $175 billion at its peak.

He also owns huge chunks of Bank of America, Coca-Cola (since 1988 — he really doesn't sell), American Express, and Chevron. Then there are the companies Berkshire owns outright.

GEICO, one of the biggest car insurers in America. Burlington Northern Santa Fe, a massive railroad.

Dairy Queen, See's Candies, Duracell. Basically a random collection of boring, cash-generating businesses that he loves precisely because they're boring.

His first fund — Buffett Partnership Ltd. — ran from 1956 to 1969.

He returned around 30% per year while the market did 8.6%. Then he shut it down, said he couldn't find enough cheap stocks, and walked away at the top.

Jim Simons

Renaissance Technologies manages several funds. The most important is the Medallion Fund, which is closed to outside investors and available only to Renaissance employees and select associates.

Medallion has returned approximately 66% gross per year since 1988 — after fees of 5% management and 44% performance, the net return to investors has been roughly 39% annualized. Over 30+ years, this makes it the best-performing investment vehicle in the history of finance, and it is not particularly close.

Renaissance also manages external funds including the Renaissance Institutional Equities Fund (RIEF) and the Renaissance Institutional Diversified Alpha (RIDA). These have performed well but not at Medallion's level — a fact that Simons has acknowledged reflects the limits of scaling the strategy to the size required by external capital.

Warren Buffett

University of Nebraska–Lincoln (B.S. in Business Administration, 1950).

Columbia Business School (M.S. in Economics, 1951) — the only school that mattered, where he studied under Benjamin Graham and got his only A+.

He also spent two years at the Wharton School before transferring. Harvard Business School rejected him.

He's described that rejection as one of the luckiest things that ever happened to him.

Jim Simons

Massachusetts Institute of Technology, BS in Mathematics, 1958. University of California, Berkeley, PhD in Mathematics, 1961.

He is the rare figure in finance whose academic credentials in their original field genuinely explain their investment success — the mathematics he learned and taught became the foundation of everything Renaissance built.