William O'Neil

Introduction

William O’Neil, best known for his CAN SLIM investing methodology, applies the same disciplined approach to short selling in How to Make Money Selling Stocks Short. His philosophy hinges on combining technical and fundamental analysis to identify weak stocks primed for decline. Unlike speculative shorting, O’Neil’s method emphasizes waiting for clear confirmation of deterioration—both in price action (technical breakdowns) and underlying business health (earnings declines). This systematic approach treats short selling not as a gamble, but as a mirror image of his buying rules, requiring patience, defined entry points, and strict risk management.

Key Concepts in O’Neil’s Short-Selling Method

The Head-and-Shoulders Pattern

O’Neil identifies the head-and-shoulders pattern as one of the most reliable reversal formations for short opportunities. The pattern consists of three peaks: a middle peak (the “head”) flanked by two lower peaks (the “shoulders”). The critical signal occurs when the stock breaks below the “neckline,” a support level connecting the lows between the peaks. “A breakdown below the neckline confirms the pattern and signals a potential short opportunity,” O’Neil writes. Importantly, the breakdown should occur on high volume, indicating institutional selling—a key distinction from false breakouts.

Breakdowns and Support Levels

A “breakdown” is a cornerstone of O’Neil’s technical approach. It occurs when a stock falls decisively below a key support level or trendline, often after a period of consolidation or distribution. “The market will tell you when it’s time to sell short; you don’t have to guess,” he emphasizes. This rule underscores the need for objective confirmation rather than anticipatory shorting. The book doesn’t specify a percentage or point drop to define a “decisive” breakdown, but the context implies a clear close below the level with accompanying high volume.

Distribution Days: Tracking Institutional Selling

O’Neil highlights “distribution days” as a warning sign of potential weakness. These are days when a stock closes lower on higher-than-average volume, suggesting institutional investors are unloading shares. While the book doesn’t quantify what constitutes “higher” volume, the emphasis is on the trend: multiple distribution days over weeks or months signal deteriorating demand. This aligns with O’Neil’s broader theme of letting the market reveal its intent rather than predicting turns prematurely.

Earnings Growth Deterioration

Fundamental weakness is non-negotiable in O’Neil’s short-selling framework. He targets companies with “poor earnings growth and deteriorating fundamentals,” particularly those where quarterly earnings growth slows significantly or turns negative after a period of expansion. The book doesn’t prescribe specific metrics (e.g., a 50% slowdown), but the qualitative deterioration is key—a company losing momentum is more vulnerable to breakdowns.

Relative Strength (RS) Line Divergence

The RS line, which compares a stock’s performance to a benchmark index, serves as an early-warning system. A declining RS line indicates underperformance, often preceding price breakdowns. O’Neil doesn’t specify how long the RS line should weaken before acting, but the trend’s direction matters more than the duration: “A declining RS line indicates underperformance and potential weakness.” This tool helps avoid shorting stocks that are merely pausing in an uptrend versus truly breaking down.

Rules in Practice

1. Never Average Down in a Short Position
   O’Neil treats this as a cardinal rule. Adding to a losing short position increases risk exponentially if the stock rebounds. Unlike buying, where averaging down can work in trending markets, shorting has theoretically unlimited upside risk.

2. Always Use Stop-Loss Orders
   The book doesn’t specify fixed percentages for stops, but the principle is clear: predefined exits prevent emotional decisions. Stops should logically be placed above recent resistance levels or the breakdown point.

3. Short Head-and-Shoulders Breakdowns
   This rule ties directly to the pattern’s reliability. Enter only after the neckline breaks with volume confirmation—no early bets.

4. Avoid Shorting Strong Uptrends
   ”Never short a stock just because it seems high-priced or overvalued.” O’Neil warns against “fighting the tape”; even overvalued stocks can keep rising. Wait for the technical and fundamental deterioration.

5. Focus on Weak Fundamentals
   Stocks with slowing earnings or negative news (e.g., missed estimates, guidance cuts) are prioritized. The technical breakdown confirms the fundamental story.

6. Wait for Confirmation
   ”The most successful short sellers are those who wait for clear evidence of weakness.” This could mean a breakdown, a series of distribution days, or an RS line rollover—but never acting on a hunch.

Lessons and Mistakes

• Shorting Without Confirmation Leads to Losses
  O’Neil stresses that “the best short sales come from stocks that have had huge price runs and then begin to show signs of topping out.” Jumping in early—before the breakdown—can trap sellers in a rally.

• Averaging Down Is Disastrous
  Unlike long positions, where dips may be buying opportunities, adding to shorts as prices rise compounds losses. The book doesn’t quantify “disastrous,” but the implication is catastrophic risk.

• Volume Confirms Breakdowns
  Ignoring volume can lead to false signals. A breakdown on low volume lacks conviction; high volume confirms institutional participation.

• Strong Earnings Growth = Dangerous Short
  Even if a stock looks technically extended, robust earnings can fuel further gains. O’Neil’s method avoids these traps by requiring fundamental deterioration first.

Closing Perspective

O’Neil’s short-selling framework mirrors his famed buying discipline: rules over instincts, confirmation over prediction. By combining technical triggers (breakdowns, volume) with fundamental decay (earnings slowdowns), he creates a systematic approach to a high-risk strategy. The lessons reiterate that shorting isn’t about timing tops but reacting to proven weakness—a reminder that patience and risk management separate successful traders from gamblers.