Investiční slovník
P/E Ratio (Price-to-Earnings): What It Says About a Stock's Value and How to Read It
Key takeaways
- P/E ratio = share price / annual earnings per share — it tells you how many times the annual earnings you are paying at purchase.
- A high P/E does not necessarily mean an expensive stock and a low P/E does not necessarily mean a cheap one — it depends on the sector, growth stage, and interest rates.
- The P/E of the S&P 500 has historically ranged between 10 and 30, with the average around 15–20 in normal market conditions.
- Watch out for losses: if a company reports a loss, the P/E is negative or undefined — the number makes no sense in that case.
- P/E is a useful quick filter but should never be used in isolation — always compare it in the context of the sector and historical average.
The P/E ratio (Price-to-Earnings, in Czech "cena k zisku") states how many times a company's annual net profit you pay when buying its shares — it is the most widely used quick valuation indicator in the equity market.
How is P/E calculated?
The formula is simple: P/E = share price ÷ earnings per share (EPS). If a share costs CZK 1,000 and the company earns CZK 50 per share annually, P/E = 20. That means you are paying 20 Czech crowns for every crown of annual earnings. Or put differently: at constant earnings the investment would pay back in 20 years.
How to read P/E in practice
Two companies with the same P/E of 20 can be very different stories:
- Low P/E (5–12): A company from a stable, slowly growing sector (banks, utilities). The market does not expect significant growth. Or the company faces problems and the market is pricing it cautiously.
- Mid P/E (15–25): The historical average for the S&P 500. Reasonable valuation for a stable company.
- High P/E (30+): The market pays a premium for expected future growth (typically technology companies). Investors are betting that earnings will grow significantly — if they disappoint, the price can fall sharply.
P/E variants you will encounter
There are several versions of P/E, depending on which "E" (earnings) you use:
- Trailing P/E: Earnings over the past 12 months — historical data, available and verifiable.
- Forward P/E: Estimated earnings for the next 12 months — includes expectations but is less reliable.
- Shiller CAPE (cyclically adjusted P/E): 10-year average adjusted for inflation — popular for evaluating entire markets and indices.
P/E for ETFs and indices
Equity index ETFs also have their own P/E — it is the weighted average P/E of all companies in the index. On the provider's website (iShares, Vanguard) or on sites like MSCI you will find the P/E for each index. It is a useful quick view of whether the whole market is historically expensive or cheap — but here too the rule holds: compare in context. More on comparing indices in the article All World vs. S&P 500.
Limits of P/E: when the number misleads
P/E does not account for: company debt, earnings quality (one-off items), currency risk, dividends, or capital intensity. That is why experienced investors also look at P/B (price-to-book), EV/EBITDA, or free cash flow yield. P/E is a good starting point, not a final verdict.
This article is educational in nature and does not constitute investment advice.
FAQ
What is the P/E ratio in simple terms?
Share price divided by annual earnings per share. The resulting number tells you how many times the annual earnings you are paying on purchase. P/E of 20 means: you pay 20 Czech crowns for every crown of annual earnings, or at constant earnings the investment pays back in 20 years.
Is a low P/E always a signal of a cheap stock?
No. A low P/E can mean a cheap stock, but also a company with problems, slow growth, or a cyclical sector. A low P/E for a bank is normal; a low P/E for a tech company may signal problems. Always compare in the context of the sector.
What is the historical P/E of the S&P 500?
The historical trailing P/E for the S&P 500 ranges roughly between 15 and 20. In low interest rate environments the market tolerates higher valuations — P/E tends to be elevated. Shiller's CAPE tracks a 10-year average and better filters out short-term earnings swings.
How do I find the P/E of an ETF?
On the provider's website (iShares, Vanguard) in the "Portfolio characteristics" or "Fund details" section. MSCI and FTSE Russell also publish P/E for their indices. It is the weighted average P/E of all companies in the index.