P/E Ratio History Chart — Price-to-Earnings Explorer

What Is the P/E Ratio?

The price-to-earnings (P/E) ratio measures how much investors are willing to pay for each dollar of a company's earnings. It is calculated as:

P/E Ratio = Stock Price ÷ Earnings Per Share (EPS)

A P/E of 20 means investors are paying $20 for every $1 of annual earnings. It is one of the most widely used metrics in equity valuation because it gives a fast, standardized way to compare how expensive a stock is relative to its own earnings history and to sector peers.

How to Interpret High vs. Low P/E Values

High P/E (typically above 25–30×): Investors expect strong future earnings growth, or the stock may be overvalued relative to current earnings. Common in high-growth technology and biotech sectors during bull markets.

Low P/E (typically below 10–15×): The stock may be undervalued, out of favor with the market, or facing earnings headwinds. Value investors often screen for low-P/E stocks trading below their historical averages.

Negative P/E: The company is reporting a net loss. The P/E ratio is not meaningful when EPS is negative — other metrics like price-to-sales or EV/EBITDA are used instead.

Historical Context Matters

A stock's P/E is most insightful when compared to its own history. A company that typically trades at 30× earnings but is currently at 15× may represent a buying opportunity — or signal a deteriorating business outlook. This tool charts P/E over time so you can see those valuation cycles clearly.

The long-run S&P 500 average P/E has hovered around 15–17×, though it expands significantly during bull markets (30–40×) and compresses during recessions (10–12×). Comparing a stock's current P/E to the broader market and its own 5-year average gives important context.

Limitations of the P/E Ratio

P/E does not account for growth rate — a company growing earnings at 40% per year justifies a higher P/E than one growing at 5%. For a growth-adjusted view of valuation, use the PEG Ratio Screener. P/E is also distorted by one-time charges, share buybacks, and accounting differences between companies. Use it alongside other signals, such as insider buying activity from the Insider Signal Screener.

Data sourced from Yahoo Finance. Enter a ticker symbol above to load the interactive P/E history chart.

Related tools: PEG Ratio Screener · Insider Signal Screener · All Stock Analysis Tools

Frequently Asked Questions

What is a good P/E ratio for a stock?

There is no universally “good” P/E ratio — it depends on the industry, growth rate, and market cycle. The historical S&P 500 average P/E is roughly 15–17×. A P/E below 15 is often considered value territory, while above 25–30 may reflect high growth expectations or overvaluation. Always compare a stock’s P/E to its own historical range and to sector peers.

Why does the P/E ratio matter?

The price-to-earnings ratio tells you how much investors are paying per dollar of a company’s annual earnings. It is one of the most widely used equity valuation metrics because it provides a quick, standardized way to compare valuations across companies and time periods. Tracking it historically reveals whether a stock is cheap or expensive relative to its own earnings history.

What does a negative P/E ratio mean?

A negative P/E ratio means the company reported negative earnings (a net loss) in the period measured. The P/E ratio is not meaningful when EPS is negative — investors typically use other metrics like price-to-sales or EV/EBITDA for unprofitable companies.

Where does this tool get its P/E data?

Historical P/E ratio data is sourced from Yahoo Finance, which provides trailing twelve-month (TTM) earnings per share and daily closing prices. Enter any US-listed ticker symbol to chart the stock’s P/E history.