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Learn Fundamental Analysis P/E, P/S, and Valuation Ratios
Intermediate 6 min read

P/E, P/S, and Valuation Ratios

How to tell if a stock is cheap, expensive, or fairly priced — and the traps to avoid.

What "Valuation" Actually Means

A stock isn't expensive at $500 or cheap at $5. Price by itself is meaningless. Valuation asks: how much are you paying for what you get?

A $500 stock that earns $50 of profit per share is cheaper than a $5 stock that earns 10 cents.

The P/E Ratio — Your First Tool

P/E = Stock Price / Earnings Per Share

If a stock is $100 and earns $5 per share, the P/E is 20. You're paying $20 for every $1 of current earnings.

Rough US-market guides:

P/E Meaning
<10 Cheap, distressed, or shrinking
10-20 Typical for mature companies
20-40 Premium for growth or quality
>40 Very expensive — needs strong future growth to justify

Always compare within an industry. A 25 P/E is normal for software but expensive for utilities.

When P/E Doesn't Work

  • Negative earnings: P/E is meaningless — use P/S
  • One-time items: Earnings can be artificially boosted or hurt by tax changes, asset sales, write-offs
  • Cyclical companies: P/E looks low at the peak of the cycle and high at the trough — exactly backwards

For unprofitable growth companies, P/S (Price-to-Sales) is more useful. Compare it to the company's history and to peers.

PEG — P/E Adjusted for Growth

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

A high P/E can be totally fair if growth is strong. Peter Lynch popularized:

  • PEG < 1.0: potentially undervalued
  • PEG ~ 1.0: fairly valued
  • PEG > 2.0: richly valued

A 40 P/E with 30% growth (PEG 1.3) can be a better deal than a 15 P/E with 0% growth (PEG ∞).

EV/EBITDA — The Pro Version

Enterprise Value (market cap + debt - cash) divided by EBITDA (earnings before interest, tax, depreciation, amortization).

Why pros prefer it: - Capital structure neutral — compares companies with different debt levels fairly - Acquirer's-eye-view — when you buy a company, you take on its debt and get its cash

Typical ranges: 8-12 (mature), 15-25 (growth), 30+ (premium / speculative).

The Value Trap

A "cheap" stock is sometimes cheap for a reason — declining business, bad management, dying industry. A 5 P/E with shrinking revenue is usually a trap, not a bargain. Always pair valuation with quality.

Cheap and good is rare. Expensive and great is common. Cheap and bad is everywhere — that's the trap.

Key Terms

P/E Ratio — Price divided by Earnings Per Share. How much investors pay for $1 of current earnings.
Forward P/E — Price divided by *expected* future earnings. Often more useful for growth stocks.
P/S Ratio — Price-to-Sales. Useful when a company isn't yet profitable.
PEG Ratio — P/E divided by earnings growth rate. Adjusts P/E for growth — a PEG below 1 is often considered cheap.
EV/EBITDA — Enterprise Value to EBITDA. A capital-structure-neutral version of P/E used for comparing across debt levels.
Not financial advice. This lesson is educational content designed for use within Fantasy Stock League. It is not an investment recommendation or a solicitation to buy or sell any security. Always do your own research and consult a licensed financial professional before making real investment decisions.

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