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PEG Ratio

PEG Ratio

The PEG ratio compares the P/E ratio to the company's expected growth rate. Values around 1 are often seen as 'fair', while much higher values can mean the stock is expensive relative to its growth.

How it relates

Trailing P/ETrailing P/E compares the current share price to the company's earnings per share over the last year. Higher P/E often reflects higher growth expectations, while lower P/E can signal lower expectations or potential undervaluation.÷Quarterly Earnings Growth (YoY)Quarterly earnings growth year-over-year shows how much profit has changed compared to the same quarter last year. Positive values mean earnings are growing; negative values mean they are shrinking.=PEG Ratio

Where it fits

Net IncomeNet income is the final profit after subtracting all expenses, interest and taxes. It is the bottom line of the income statement and represents the earnings available to shareholders.→Trailing P/ETrailing P/E compares the current share price to the company's earnings per share over the last year. Higher P/E often reflects higher growth expectations, while lower P/E can signal lower expectations or potential undervaluation.→PEG Ratio
PEG Ratio→Valuation

The PEG ratio (Price/Earnings to Growth) refines the P/E ratio by incorporating expected earnings growth, addressing a major limitation of P/E—that it doesn't account for different growth rates among companies. A stock with a P/E of 30 might be expensive for a slow-growing utility but cheap for a company doubling earnings annually.

The calculation divides P/E by expected earnings growth:

PEG Ratio = P/E Ratio / Annual Earnings Growth Rate (%)

For example, a stock with a P/E of 20 and expected 20% annual earnings growth has a PEG of 1.0 (20 ÷ 20). A company with the same P/E but only 10% growth has a PEG of 2.0 (20 ÷ 10).

Common interpretation guidelines:

  • PEG < 1.0: Often considered undervalued relative to growth prospects
  • PEG = 1.0: Traditionally viewed as "fairly valued"—you pay $1 in P/E for each 1% of growth
  • PEG > 1.0: May be overvalued relative to growth, or the market expects acceleration
  • PEG > 2.0: High premium being paid for growth; risk of disappointment

Peter Lynch popularised the PEG ratio, suggesting stocks with PEGs below 1.0 while avoiding those above 2.0. However, context matters significantly.

Important considerations:

  • Growth estimate source: Use consistent growth estimates (e.g., 5-year projected growth) across comparisons
  • Growth sustainability: High current growth may not persist; PEG assumes continued growth
  • Quality factors ignored: Two companies with identical PEGs may have vastly different risk profiles
  • Negative or zero growth: PEG is meaningless for declining or stagnant companies
  • Interest rate environment: Low rates justify higher PEGs; high rates demand lower ones

The PEG ratio works best when comparing similar companies in the same industry with positive expected growth. It's less useful for cyclical businesses, turnarounds, or mature companies with minimal growth. Use it as one input among many rather than a standalone decision tool.