📖Bill Ackman
Probabilistic Thinking
Think in probabilities, not certainties.
Think in probabilities, not certainties. Every investment has a range of possible outcomes. Weight your decisions by the expected value of each scenario.
🏠 Everyday Analogy
📖 Core Interpretation
In Probabilistic Thinking, Bill Ackman focuses on the gap between price and value. Returns come from paying less than what a business is worth, not from guessing short-term market moves.
💎 Key Insight：Expected value calculations guide rational decisions.
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❓ Why It Matters
Ignoring valuation turns even good companies into poor investments. Overpaying compresses future returns and leaves little margin when assumptions are wrong.
🎯 How to Practice
Estimate intrinsic value with conservative assumptions, set clear buy ranges, and act only when price offers a meaningful discount with acceptable downside.
⚠️ Common Pitfalls
Confusing a low price with true cheapness
Using one metric without business context
Overly optimistic assumptions that erase margin of safety
📚 Case Studies
1
Warren Buffett’s Dempster Mill Disaster (1962)
Buffett bought Dempster Mill, a windmill manufacturer, very cheaply, assuming mean reversion in earnings. Operations kept deteriorating; management was weak and the industry structurally challenged. The investment stagnated for years and consumed attention and capital before Buffett brought in new management and eventually liquidated/sold assets.
✨ Outcome：Buffett concluded that buying mediocre businesses just because they’re cheap is dangerous. He shifted toward “wonderful businesses at fair prices,” paving the way for Berkshire’s focus on quality franchises like See’s Candies and Coca‑Cola.
2
Long-Term Capital Management’s Near-Collapse (1998)
LTCM, led by John Meriwether with Nobel laureates, used heavy leverage to exploit tiny arbitrage spreads. In 1998, Russia’s default triggered a global flight to quality; LTCM’s positions moved violently against them. With leverage over 25–30x, losses spiraled, forcing a Fed-brokered Wall Street bailout.
✨ Outcome：The episode highlighted that historical models can fail in extreme conditions and that leverage amplifies small errors into existential threats. Many future hedge fund managers reduced gross and net leverage and improved stress testing and liquidity risk management.
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