PEG Ratio
Key Takeaways
- PEG Ratio = P/E Ratio / Earnings Growth Rate
- A PEG of 1.0 suggests the stock is fairly valued for its growth rate
- PEG below 1.0 may indicate undervaluation; above 2.0 may indicate overvaluation
- Combines valuation and growth in a single metric
Definition
The PEG ratio (price/earnings-to-growth) adjusts the P/E ratio for the company's expected earnings growth rate, providing a more nuanced valuation measure. While P/E alone might suggest a high-growth stock is expensive, the PEG ratio reveals whether the premium is justified by the company's growth trajectory.
PEG = P/E Ratio / Annual EPS Growth Rate (%). A stock with a P/E of 30 and an earnings growth rate of 30% has a PEG of 1.0 — its growth rate fully supports its P/E. The same P/E with only 15% growth has a PEG of 2.0 — it may be overvalued relative to growth.
The PEG ratio was popularized by Peter Lynch, legendary manager of the Fidelity Magellan Fund, who used it to find "Growth at a Reasonable Price" (GARP) opportunities. He considered a PEG of 1.0 as the threshold for fair valuation.
How It Works
PEG = P/E / EPS Growth Rate. The growth rate can be based on historical growth, analyst consensus estimates for the next 1-2 years, or projected long-term growth. Using estimated future growth is more forward-looking but introduces forecast uncertainty.
Interpretation: PEG < 1.0 — potentially undervalued for its growth rate. PEG = 1.0 — fairly valued based on growth. PEG 1.0-2.0 — may be somewhat overvalued. PEG > 2.0 — likely overvalued unless growth estimates are conservative.
PEG works best for companies with positive and relatively stable earnings growth. It is less useful for companies with negative earnings, cyclical earnings patterns, or growth rates that are expected to change significantly.
Example
Compare three stocks: NVIDIA (NVDA) with P/E of 35 and expected growth of 30% (PEG = 1.17). Coca-Cola (KO) with P/E of 24 and expected growth of 7% (PEG = 3.43). Alphabet (GOOGL) with P/E of 22 and expected growth of 15% (PEG = 1.47). Despite having the highest P/E, NVIDIA has the lowest PEG because its growth rate justifies the premium. Coca-Cola has the highest PEG, suggesting its P/E premium may not be supported by its modest growth rate. Alphabet falls in between as a reasonably priced growth stock.
Why It Matters
The PEG ratio solves a key problem with P/E ratios: they do not account for growth. A 40x P/E stock growing earnings at 40% per year is a better value than a 15x P/E stock growing at 5%. Without PEG, investors might incorrectly assume the lower P/E stock is cheaper.
PEG is particularly useful in growth investing for separating reasonably priced growth stocks from overvalued hype. During market euphoria, many stocks trade at PEGs of 3-5x or higher — a warning sign that valuations have disconnected from growth fundamentals.
Advantages
- Incorporates growth rate into valuation for more nuanced comparison
- Helps identify undervalued growth stocks (PEG < 1.0)
- Simple to calculate and widely understood
- Useful screen for GARP investing strategy
Limitations
- Depends entirely on the accuracy of growth estimates
- Less useful for companies with negative, zero, or volatile earnings
- Does not account for risk differences between companies
- Growth rate time horizon (1-year vs. 5-year) significantly affects results
Frequently Asked Questions
Related Terms
Browse more definitions in the financial terms glossary.