Understanding whether a stock is expensive or cheap is one of the first skills every investor should learn. The **Price/Earnings ratio**, or **P/E ratio**, is one of the most fundamental valuation metrics used to answer this question. Widely used by both individual and institutional investors worldwide, this ratio is also an indispensable tool for stock selection on BIST.
What Is the P/E Ratio?
The P/E ratio is a valuation multiple obtained by dividing a company's market price by its earnings per share. This ratio shows how many liras an investor pays for every 1 TL of earnings. In other words, it provides a rough estimate of how many years it would take to recoup your investment at the company's current profitability level.
For example, if a stock has a P/E ratio of 8, buying it at today's price and assuming the company continues to earn the same profit, you would recoup your investment in approximately 8 years. Of course, this is a simplified approach; in reality, profitability changes, dividend policies differ, and growth expectations directly affect pricing.
How Is the P/E Ratio Calculated?
Calculating the P/E ratio is straightforward. You need two basic components: the stock's current market price and earnings per share (EPS). The formula is:
**P/E Ratio = Share Price / Earnings Per Share (EPS)**
Earnings per share is calculated by dividing the company's total net income by the number of shares outstanding. Alternatively, you can divide the company's total market capitalization by total net income to reach the same result.
Practical Example: Calculating P/E on BIST
Suppose EREGL's stock price is 50 TL and its trailing twelve-month earnings per share is 6.25 TL. The P/E ratio would be 50 / 6.25 = 8. This means investors are willing to pay 8 TL for every 1 TL of EREGL's earnings.
An important point to consider when calculating the P/E ratio is which earnings data you are using. **Trailing P/E** uses the most recent 12 months of actual earnings. **Forward P/E** is based on analyst estimates for the next 12 months of expected earnings. Each approach has its advantages and limitations.
How to Interpret the P/E Ratio
When interpreting the P/E ratio, looking at a single number alone is not enough. Context is everything. A low P/E does not always mean cheap, and a high P/E does not always mean expensive. To interpret correctly, you need to make several key comparisons:
- **Sector comparison:** Place the P/E ratios of companies in the same sector side by side. The banking sector typically trades at a 4–7 P/E range, while technology companies may be at 15–30. Comparing GARAN and AKBNK (banks) with ASELS (defense) on a P/E basis would give misleading results.
- **Historical comparison:** Compare the stock's current P/E to its own historical average. If a stock has historically traded at 10x P/E but is currently at 6x, it may potentially be cheap.
- **Growth expectation:** Fast-growing companies naturally trade at higher P/E ratios because investors may be pricing in future earnings growth.
- **Market environment:** During periods of high inflation and interest rates, P/E ratios on BIST generally compress. In low-rate environments, they expand. In a market like Turkey with intense macroeconomic fluctuations, this must be taken into account.
Beware the Low P/E Trap
One of the most common mistakes inexperienced investors make is automatically treating a low P/E ratio as an opportunity. However, there can be many negative reasons for a stock's low P/E: the company's profitability may be declining, there may be sector-wide problems, or serious concerns about management quality. This is called a **value trap**.
For example, in cyclical sectors (steel, energy), when companies report record profits, their P/E ratios appear very low. But these profits may reflect the peak of the cycle, with significant declines ahead. This is why looking at P/E alone for steel producers like EREGL is not enough — you should also evaluate steel price cycles and capacity utilization rates.
The Inverse of P/E: E/P (Earnings Yield)
The inverse of the P/E ratio, **E/P (Earnings Yield)**, gives investors a different perspective. E/P = 1 / P/E, expressed as a percentage. If a stock has a P/E of 8, its earnings yield is 12.5%. This ratio makes it easier to compare equity returns against bond yields or deposit rates.
In borsafolio.com's stock screener, you can directly access E/P data and sort BIST stocks by earnings yield. This feature is particularly useful for those who want to evaluate equity attractiveness relative to bonds in a high interest rate environment.
P/E Ratio: Frequently Asked Questions
**What does a negative P/E ratio mean?** If a company is making losses, the P/E ratio turns negative. The metric is meaningless for companies with negative P/E; alternative valuation methods like P/B or revenue multiples should be used instead.
**What is a good P/E ratio for BIST?** There is no single answer. However, the BIST-100 index has historically traded at an average P/E in the 7–10 range. This reference point varies depending on the sector, growth expectations, and macroeconomic conditions.
**Is the P/E ratio sufficient on its own?** Absolutely not. The P/E ratio is just one piece of the valuation puzzle. It should be evaluated alongside P/B, EV/EBITDA, dividend yield, and other metrics. borsafolio.com's stock screener offers all of these metrics together, enabling comprehensive analysis.
Summary
The P/E ratio is one of the most fundamental and widely used metrics in stock valuation. When used correctly, it provides a quick sense of a stock's relative cheapness or expensiveness. However, like any metric, it is not sufficient on its own. It reveals its true power when evaluated alongside sector comparisons, historical analysis, and other financial ratios. When investing on BIST, view the P/E ratio as one of the cornerstones of your toolkit — but not your only tool.
