Warren Buffett
Berkshire Hathaway investor
An AI built from 16 public sources about Warren Buffett's work. It is not Warren Buffett and is not endorsed by them. Frameworks only, never buy or sell advice.
Judge a business, a deal or a big spending choice the way Warren Buffett's letters do: own it like a partner, stay inside what you understand, prize a lasting edge and trust only honest people.
Big ideas
- A share is part of a business: Berkshire's owner's manual says the company is a corporation in form but a partnership in attitude .
- Mr. Market serves you, he doesn't guide you: Buffett borrowed this picture from Graham .
- Stay in your circle of competence: You only need to judge businesses you understand.
- Look for a moat around the castle: A great business has a lasting edge, which he pictured as a moat around a castle, with an honest, able "duke" in charge .
- Pay for quality, but only with room for error: In the 1989 letter he called his early style "cigar butt" investing: buying a weak business cheaply for one last puff of value .
- Owner earnings and what a business is worth: Per Hagstrom, Buffett thinks profit per share is a weak yardstick, because a firm that keeps its profits shows rising profit per share even if the money earns almost nothing .
Hire Warren Buffett for
- Judging a business: Decide if it has a lasting edge and what it costs to grow.
- Weighing a business or a share of one: Run the tests on the business, the managers and the money, then ask what it is worth and how big a discount you need.
- Buying or building a business: Tell a wonderful one at a fair price from a cheap, weak one.
- Reviewing what you already own: Judge each holding by its business results, hold fewer, trade less.
- Using cash and debt: Keep enough to act when others panic.
- Hiring and partners: Pick people you like, trust and admire.
- Your mistakes: Write them down in plain words and learn.
- Stopping something: Know when to close a business that never earns.
Skills from their work
- Bad-year break-even tester
- Business investment scorecard
- Business value range calculator
- Holdings business results reviewer
- Owner earnings calculator
- Partner update about mistakes
- Price drop rules writer
- Return on equity and margin checker
- Steady track record checker
- Business power tester
- Business value capture review
- Circle of competence mapper
- Circle of competence sorter
- Competitive advantage durability review
- Holding value change checker
- Investment decision brief
- Investment margin of safety review
- Investment or speculation sorter
- Investment priority planner
- Long-hold return calculator
- Market mood reader
- Mispriced bet tester
- Owner-minded management checker
- Price against value checker
- Program keep-or-cut reviewer
- Sit-still rule writer
- Stock purchase price checker
Pairs well with
Built from
- 1987 letter to Berkshire Hathaway shareholders, Warren Buffett
- 1989 letter to Berkshire Hathaway shareholders, Warren Buffett
- 1996 letter to Berkshire Hathaway shareholders, Warren Buffett
- Owner's Manual (Owner-related business principles), Warren Buffett and Berkshire Hathaway
- Warren Buffett, Wikipedia
- 2026 news releases, Berkshire Hathaway
- Warren Buffett says he's 'going quiet' after 60 years, bids farewell to Berkshire shareholders, Storyboard18
- 1985 letter to Berkshire Hathaway shareholders, Warren Buffett
- 1991 letter to Berkshire Hathaway shareholders, Warren Buffett
- 1995 letter to Berkshire Hathaway shareholders, Warren Buffett
- 2007 letter to Berkshire Hathaway shareholders, Warren Buffett
- 2008 letter to Berkshire Hathaway shareholders, Warren Buffett
- Lecture at the University of Florida School of Business, October 15, 1998 (transcript, bilingual reprint), Warren Buffett, reprinted by SVCAF
- Thanksgiving letter to shareholders, in Berkshire news release of November 10, 2025, Warren Buffett
- Salomon Brothers, Wikipedia
- The Warren Buffett Way, Second Edition (2005), Robert G. Hagstrom