Only buy something that you'd be perfectly happy to hold if the market shut down for 10 years.
Source: Berkshire Hathaway Letters · Markets
Core Idea
Invest in businesses you truly understand and believe in long term, prioritizing durable value and fundamentals over short-term market fluctuations, price quotes, or speculative trading opportunities.
Practical Application
Before buying any stock, ask if you would confidently own the underlying business for a decade without checking prices; if not, reconsider your understanding, conviction, and time horizon.
Why It Matters
The insight is that true investing means treating stocks as whole businesses, demanding deep understanding, durable advantages, and long-term confidence rather than reacting to daily market noise or price movements.