CAN SLIM — The Anatomy of a Market Leader

William O'Neil studied every major winning stock from 1880 to the present and asked a simple question: what did they all have in common just before their biggest price moves? The answer — seven specific, measurable characteristics — became the CAN SLIM system.

Why This Matters

William O'Neil founded Investor's Business Daily in 1984 after spending years studying market history with a rigour that few practitioners have matched. His central project was inductive rather than theoretical: instead of building a model of how markets should work and testing it, he examined what the biggest winning stocks of history actually looked like before their major advances — and derived the common characteristics empirically. The result was CAN SLIM — an acronym covering the seven characteristics most predictive of significant price appreciation. It is deliberately hybrid: fundamental analysis (earnings quality, growth acceleration, new products) combined with technical analysis (market leadership, price and volume behaviour). O'Neil argued that neither approach alone was sufficient. Strong fundamentals without institutional sponsorship often sit undervalued indefinitely. Strong technicals without fundamental support tend to be speculative and fragile.