Summary and review ofThe Intelligent Investor

Reviewed by Diario de un Inversor · UpdatedJune 13, 2026

Our review

The Intelligent Investor is the founding text of value investing: Benjamin Graham, Warren Buffett's professor at Columbia, separates the investor from the speculator and argues for buying businesses below their intrinsic value with a margin of safety. The book defines two profiles, the defensive investor (who wants simplicity and protection) and the enterprising one (willing to do more analysis), and gives each a different strategy. Its most famous contribution is the allegory of "Mr. Market", a manic-depressive partner who quotes you a price every day: the point is not to follow his mood but to exploit his excesses. Graham also warns about inflation, leverage and the value of a proven record over growth promises. It is not light reading: there are tables, ratios and accounting examples that demand attention. Yet its philosophy —discipline, patience and temperament over talent— still holds more than seventy years later, and explains much of the success of the investors who have applied it.

Key takeaways

• Investing means operating with a margin of safety; speculating bets on price.
• "Mr. Market" offers irrational prices to exploit, not to obey.
• Temperament and discipline matter more than IQ.
• The defensive and the enterprising investor need different strategies.

Fact

Published in 1949; Warren Buffett has called it "by far the best book on investing ever written".