Price-to-Earnings Ratio (P/E)

Explanation

The P/E ratio is the most widely used valuation metric in equity analysis. It divides a company's share price by its earnings per share (EPS). A P/E of 20 means investors are paying $20 for every $1 of annual profit.

Two versions exist: trailing P/E uses the last 12 months of actual earnings, while forward P/E uses analyst estimates for the next 12 months. Forward P/E is generally more useful for investment decisions because markets price future expectations.

The S&P 500's average P/E has historically ranged between 15 and 20. During the dot-com bubble (2000), it reached 44. During the 2008 financial crisis trough, it fell below 10. Context matters—growth companies typically command higher P/Es because their earnings are expected to grow faster.

Formula

Example

Apple trades at $195 per share. Its trailing twelve-month EPS is $6.50. Its forward EPS estimate is $7.10.

Investors are paying 30 times current earnings or 27.5 times expected earnings. The lower forward P/E suggests analysts expect 9.2% earnings growth. Whether 30x is cheap or expensive depends on Apple's growth rate and the market environment.

How Stoquity Uses This

Stoquity's factor scoring model includes P/E as a component of the Value factor. The AI engine compares each stock's P/E to its sector median and historical range. Stocks trading below their 5-year average P/E score higher on value; those trading above score lower.

Common Mistakes

• A low P/E is not automatically cheap—it may reflect declining earnings or structural problems
• Comparing P/E ratios across sectors is misleading; tech companies naturally have higher P/Es than utilities
• Negative earnings make the P/E ratio meaningless, which is why other metrics like P/S are used for unprofitable companies