PER, PBR, ROE: The 3 Key Metrics Every Stock Beginner Must Know

PER: How Expensive Is the Stock Relative to Earnings?

PER (price-to-earnings ratio) is calculated as price divided by earnings per share (EPS). Put simply, it's a number showing "if I bought this whole company now, how many years would it take to recover my principal from the earnings it makes now."

Let me give a simple hypothetical example. If a company's PER is 10x, that means the stock price is 10 times the profit the company earns in a year. Assuming it earns the same profit every year, it would take 10 years to earn back what you paid. A PER of 20x means 20 years, and 5x means 5 years. The larger the number, the more the market is paying for that profit.

Here a key question arises. Why is one company's PER 5x and another's 30x? Because the market expects future earnings growth differently. A company expected to grow fast is assigned a high PER even if its current profit is small, while one seen as growing slowly stays at a low PER.

So you can't say a low PER means "cheap" or a high PER means "expensive," no exceptions. A low PER may be a signal that the market sees the company's future darkly, and a high PER may reflect growth expectations. PER's meaning comes alive when you compare companies in the same industry with a similar character. Setting a fast-growing IT company side by side with a stable bank on PER alone is like comparing apples and pears by weight only.

PBR: Where Does the Stock Stand Relative to Assets?

PBR (price-to-book ratio) is price divided by net assets per share. Net assets are all the assets the company holds minus the debt it must repay, in other words the company's book value. A PBR of 1x means the stock price equals the book net assets; below 1x means it trades cheaper than book value, and above means more expensively.

By analogy, if PER looks at "the money this shop earns," PBR looks at "the assets this shop holds." It's used especially often in industries with lots of tangible assets like real estate, facilities, and cash, such as banking, steel, and shipbuilding.

But PBR has its traps too. First, book value can differ from actual value. An old plant may be recorded large on the books yet be worn out and of little real use, and conversely, intangible value like brand and technology, which doesn't show up well on the books, is left out. That's why asset-light software and platform companies tend to show high PBRs, but this is not because they're expensive; it's merely an industry characteristic. Second, a low PBR isn't necessarily undervaluation. For a company that can't make money and keeps eating into its assets, a low PBR may instead be the shadow of insolvency.

ROE: How Well Does It Earn with Its Own Money?

ROE (return on equity) is net profit divided by shareholders' equity, showing "what percent of profit it made in a year with the money shareholders entrusted." If the previous two metrics ask whether the stock price is fair, ROE asks whether the company is good at business.

For example, if a company with equity of 100 made a net profit of 10 in a year, its ROE is 10%. If it earns 20 with the same money, that's 20%. Think of it as watching, like a bank deposit, what percent the entrusted money grows by on its own. Generally, a company with consistently high ROE is rated as one with strong earning power. Conversely, if ROE stays low or is erratic for years, it can be read as a signal that the business's profitability is unstable.

However, you can't take ROE at face value either. Because ROE's denominator is equity, if a company borrows heavily, the figure can be inflated even with the same profit. In other words, you have to distinguish whether a high ROE is thanks to outstanding business ability or to risky debt. Also, if a one-off gain like a real estate sale enters a particular year, ROE can spike briefly and then fizzle the next year, so you should view it over the trend across several years, not a single year.

Why You Have to Look at the Three Metrics Together

The three metrics illuminate the company from different angles. PER is price relative to earnings, PBR is price relative to assets, and ROE is earning efficiency. Looking at only one creates an optical illusion. For instance, if ROE is high so the business is good but PER and PBR are also high, expectations may already be heavily reflected; and if PBR is low while ROE is also low, there's a reason it's cheap. Only when you overlay the three does a three-dimensional picture emerge. Even so, you mustn't forget that these numbers are only a snapshot of the past and present, and don't guarantee the future.

Common Misconceptions

• "A low PER means it's undervalued, no question." No. It may reflect the market's judgment that growth has stalled or risk is high.
• "Below a PBR of 1x is definitely cheap." If the company is eating into its assets because it can't earn, the book value itself is wobbling.
• "If ROE alone is high, it's a good company." It can be inflated by excessive debt or one-off gains, so you have to look at leverage and sustainability together.
• "Knowing just these three metrics lets you pick stocks." They are only a starting point; you have to look at them together with the business model, industry conditions, and financial soundness.

Frequently Asked Questions (FAQ)

What PER is appropriate?

There's no absolute standard that holds across all industries. It's natural for it to form high in industries with big growth expectations and low in mature industries. So it's realistic to compare similar companies within the same industry, and with that company's own past trend.

What if I had to look at only one of the three?

Judging by a single metric is itself not recommended. Rather than forcing a choice, it's safer to understand that the three metrics answer different questions and to reference them together.

Can these metrics tell me whether the stock will rise?

No. Metrics are a tool for interpreting the current state, not a device for predicting the future. The same number is received differently depending on industry conditions, interest rates, and sentiment.

This article is for informational purposes only and is not a recommendation to buy or sell any particular stock. Investment decisions and their consequences rest with the investor.