Buffett’s Golden Rule: Don’t Lose Money
The entire philosophy of value investing is built on a foundation of capital preservation. As Warren Buffett stated: Rule #1 is Don’t Lose Money. Rule #2? Don’t Forget Rule #1.
It sounds simple, yet it’s often forgotten when markets are driven by the herd mentality of fear and greed. This core tenet teaches us to wait for the inefficiency in the market—the moments when prices become “nonsensical”—and buy a business for less than its true value. This is the essence of having a Margin of Safety.
An often-cited benefit of stocks is their hedge against inflation: Stock markets, however, typically rise with inflation because company revenue and earnings typically rise commensurately. In sum, inflation hurts savings but helps stocks.
Sanity Checks for Market Pricing
Before diving into individual stocks, Rule #1 investors check the temperature of the overall market to avoid buying during times of widespread overvaluation.
| Indicator | Formula / Definition | Valuation Range & Context |
| Shiller P/E (CAPE) | Cyclically Adjusted Price-to-Earnings Ratio: The S&P 500’s price divided by the average of the last 10 years of inflation-adjusted earnings. | Provides a long-term sanity check to determine how over- or underpriced the market is. |
| Buffett Indicator | Wilshire 5000 Total Market Cap / U.S. GDP. | ≈60%: Market is priced under its real value (overall undervalued). |
| >100%: Market is overpriced (e.g., as seen preceding the 2000 and 2008 crashes). |
Charlie Munger’s Four Principles of Investing
Charlie Munger’s approach adds depth and sophistication to Buffett’s simple rules, guiding investors to look for quality over simply cheapness. His famous quote is the key: “It’s better to buy a wonderful business at a fair price than a fair business at a wonderful price.”
Here are the four criteria a company must meet for Munger (and Town) to invest:
1. Be Capable of Understanding (Circle of Competence)
You should only invest in businesses you can comfortably predict the long-term prospects of. This is your Circle of Competence.
- Actionable Step: Use the “three-circles exercise” (What you’re passionate about, what you vote for with your money, and where you make your money) to define your focus and avoid investing on the edge of your knowledge. If you can’t describe the business and industry in one paragraph, it’s Too Hard.
2. Intrinsic and Durable Competitive Advantage (The Moat)
A “wonderful business” is protected from competition by a Moat. This is a durable, intrinsic characteristic that allows the business to maintain its high returns.
The Five (and a Half) Moats are:
- Brand: A strong, difficult-to-replicate reputation (e.g., Coca-Cola).
- Switching: Difficulty, pain, or expense for a customer to move to a competitor (e.g., Apple’s integrated ecosystem).
- Network Effects (The Half-Moat): The value of the product increases as more people use it (a subset of Switching) (e.g., Facebook).
- Toll Bridge: A monopoly or near-monopoly in a big niche (e.g., a dominant pipeline or essential utility).
- Secrets: Proprietary secrets, patents, or protected intellectual property (e.g., a pharmaceutical patent).
- Price: Being the intrinsically sustainable low-cost provider (e.g., Costco).
3. Management with Integrity and Talent
You are partnering with the people running the business. They must be trustworthy and capable.
- Key Insight: Look for executives who act like owners (high shareholding stake) and speak with intellectual honesty in shareholder letters, using vocabulary like “per share growth” “return on invested capital”, and “free cash flow,” which indicates a value-investing mindset.
4. A Price That Makes Sense and Has a Margin of Safety
Buy a business only when its price is on sale. This is the protective buffer against the “vicissitudes of life.”
- The Event: A Rule #1 Event is a temporary and rectifiable disaster (economic recession, scandal, poor quarterly earnings) that creates market fear and drives the stock price down, putting a wonderful business “on sale.” The key is that it is temporary.
Essential Financial Metrics: The Big Four & Management Numbers
The Big Four Growth Rates (The Company’s Health)
These metrics, found in a company’s financial statements, should be consistently and predictably growing at 10% or better each year to signal a wonderful business.
| Financial Metric | Source | Definition | Example of Growth |
| Net Income (or Net Profit/Earnings) | Income Statement | The company’s total profit after all costs have been deducted. | A company’s net income rose from $10M to $11.5M in a year, a 15% growth rate. |
| Book Value + Dividends (if any) | Balance Sheet (Equity) / Cash Flow Statement (Dividends) | The residual value of the business if all assets were sold and liabilities paid (Equity). Must be growing to show value retention. | If a company’s assets ($100M) minus its liabilities ($40M) equals a book value (equity) of $60M. |
| Sales (or Revenue) | Income Statement | The total amount earned from selling goods or services. | A company’s annual sales increasing year over year demonstrates market demand for its products. |
| Operating Cash Flow | Cash Flow Statement | The actual cash generated by the company’s normal business operations. | High and growing cash flow means the company has money to reinvest or distribute to owners. |
Management Numbers (Efficiency and Safety)
These metrics assess how effectively and safely the management team is using shareholder capital.
| Financial Metric | Formula | Definition | Benchmark |
| Return on Equity (ROE) | Net Income/Equity | How much profit the company generates for each dollar of shareholder equity. | 15% or better, each year, for the last ten years or so, to prove durability. |
| Return on Invested Capital (ROIC) | Net Income/(Equity+Debt) | How efficiently the company is using all its capital (both equity and debt) to generate a return. | 15% or better, each year, for the last ten years or so, is a sign of a strong Moat. |
| Debt | Balance Sheet | The total long-term debt held by the company. | The company must be able to pay off all long-term debt with one to two years of earnings (or Free Cash Flow). Excessive debt is corrosive. |
Valuation Methods: Finding the Margin of Safety
Rule #1 investors use different methods to determine the Sticker Price (the reasonable value) and then apply a discount to get the Margin of Safety Buy Price.
1. Owner Earnings & The Ten Cap Price
Owner Earnings is the true cash flow available to the owner without affecting the business’s competitive position.
Owner Earnings=Net Income+ Depreciation & Amortization + Δ Accounts Receivable + Δ Accounts Payable + income tax (if adjusted as laid out in text)−Maintenance Capital Expenditures
The Ten Cap Price requires a 10% return on investment per year (a cap rate of 10).
Ten Cap Buy Price=Owner Earnings×10
2. Free Cash Flow & Payback Time Price
Free Cash Flow (FCF) is the cash from operations remaining after accounting for capital expenditures. The Payback Time Price determines how long it will take to get your initial purchase price back.
FCF = Net Cash from Operating Activities + (Purchase of Property & Equipment) [this line is negative on statements] + Other Maintenance/Growth CapEx [usually negative]
- Goal: A Payback Time of eight years or less is considered a sensible price, as it is roughly half of the average public company valuation (about 16 years of FCF), providing a 50% Margin of Safety.
3. Margin of Safety (MOS) Method (The Sticker Price)
This method works backward from a projected future price to determine today’s maximum price while demanding a Minimum Acceptable Rate of Return (MARR) of 15% per year.
- Project Future EPS: Grow the current Earnings Per Share (EPS) for ten years using the conservative Windage Growth Rate (your comfortably certain growth estimate).
- Calculate Future Share Price: Multiply the Future EPS by a conservative Windage P/E Ratio (the lower of 2× Windage Growth Rate or the historical high P/E).
- Find Sticker Price (PV): Discount the Future Share Price back to today using the 15% MARR.
Sticker Price=Future 10-Year Share Price/(1.15)10
Patience, Preparation, and Inversion
The journey requires patience—waiting for the great company to go on sale. When fear is everywhere, you must be ready to act aggressively with investing funds available.
A critical tool to prevent confirmation bias is Inversion—cross-examining your own argument by proving the opposite. Take your best reasons to buy a company and honestly try to prove they are wrong. If, after inverting the story, you are more certain about the company, you’ve done your work.
Investing in tranches (slices/portions) is a smart way to deploy capital during a falling price, taking advantage of the opportunity to buy a great business at ever-cheaper prices.
Finally, the greatest secret to compounding returns: The right time to sell a company is never, unless the company’s Story (Mission, Moat, or Management) fundamentally changes. If you bought a wonderful business at a wonderful price, hold on for the long haul.