📖William Gann

Probabilistic Thinking

🌳 Advanced★★★★★

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.

— 45 Years in Wall Street,1949

🏠 Everyday Analogy

Valuation is like buying a house: the asking price reflects mood, but true value comes from structure, location, and long-term utility. Good assets still need sensible prices.

📖 Core Interpretation

In Probabilistic Thinking, W.D. Gann 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
Dot-Com Bubble Peak (2000)
The NASDAQ in early 2000 broke its prior swing lows, forming a clear downtrend per Gann’s rule of lower highs and lower lows after a parabolic rise.
✨ Outcome:Investors who sold when the trend reversed sidestepped years of heavy tech stock drawdowns.
2
Dow Jones Crash and Gann Retracements (1929)
After the 1929 peak near 381, the Dow plunged and later retraced key Gann levels, notably around the 50% and 62.5% zones, signaling potential resistance and trading opportunities for disciplined followers of percentage retracement rules.
✨ Outcome:Traders using Gann retracements managed risk, capturing partial rebounds while avoiding full re-entry before a durable long-term bottom.

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