When Is a Stock Cheap? How to Tell Undervalued From Overvalued

A stock is cheap when its price sits well below a conservative estimate of what the business is worth, and expensive when the price already assumes everything will go right. The share price alone tells you nothing: a $400 stock can be cheap and an $8 stock can be expensive. What matters is the gap between price and value, and whether that gap exists for a good reason.

Where this fits: this article is a practical guide to criterion 5, reasonable price, in the Five Criteria. For the building blocks of valuation, see what is stock valuation.

Price Is What You Pay, Value Is What You Get

Warren Buffett has often repeated a line he credits to Benjamin Graham: price is what you pay, value is what you get. That one sentence clears up most confusion about “cheap” stocks.

A share price only means something next to the business behind it. A stock at $8 with no profits and shrinking sales can be very expensive. A stock at $400 that earns $30 per share in free cash flow is, at a 7.5% yield, arguably cheap.

So “Is this stock cheap?” really means: am I buying more value than I am paying for, with enough room left over in case I am wrong?

How to Tell If a Stock Is Undervalued: Four Tests

No single number answers the question. I use four tests together and look for them to agree.

Test 1: Discount to intrinsic value

This is the most important test and the hardest. You estimate what the business is worth from the cash it will generate, then compare that value with the price.

Three common approaches:

• Discounted cash flow (DCF). Project free cash flow, then discount it back to today at your required return. Our DCF guide walks through it.
• Earnings power value. Divide sustainable, normalised earnings by your required return. A company earning a steady $2 per share, valued at a 10% required return, is worth about $20 with no growth assumed.
• Multiples of similar businesses. Compare the price-to-earnings or EV/EBIT multiple with those of similar-quality companies.

Each method has flaws, so use more than one and work with a range rather than a single number.

Test 2: Cash yield

Flip the valuation multiple over and ask what return the business generates on today’s price. A stock at $50 with $3.50 of free cash flow per share has a 7% free cash flow yield. That is the cash the business produces for each dollar you pay, before any growth.

Joel Greenblatt popularised a version of this in The Little Book That Beats the Market, where he ranked companies on earnings yield, defined as operating profit (EBIT) divided by enterprise value. The idea is the same: a higher yield means you pay less for each dollar of earnings.

A useful rule of thumb: compare the yield with what you could get risk-free from a government bond. If a stock’s cash yield is barely above the bond yield, you are relying heavily on growth to earn a decent return.

Test 3: Discount to its own history

Look at the multiples the company has traded at over the past five to ten years. If a business has usually traded at 15 to 20 times earnings and now trades at 11, it may be cheap. Or something may have broken. This test tells you where to dig, not what to conclude.

Test 4: Discount to peers

Compare the stock with direct competitors of similar quality. If it trades at 12 times free cash flow and comparable peers trade at 18 to 20, ask why. Sometimes the market has simply overlooked it. Often the cheaper company is also the weaker one.

When Is a Stock Expensive? Warning Signs of Overvaluation

Spotting an expensive stock is harder than spotting a cheap one, because expensive stocks are usually attached to excellent businesses. Great companies attract crowds. The crowd bids up the price until a wonderful business becomes a poor investment.

Warning signs that a stock has become expensive:

• Multiples far above its own history. A company that traded at 12 to 16 times earnings for a decade now trades at 30. Ask what has changed in the business to justify double the valuation. If the honest answer is “the story got more popular,” be careful.
• A premium to peers with no clear reason. A premium can be earned through faster growth, higher returns on capital or a wider moat. A premium based only on enthusiasm tends not to last.
• A very low cash yield. A free cash flow yield near 1% or 2% means you are relying almost entirely on many years of strong growth to earn a decent return.
• A valuation that needs everything to go right. Small, reasonable changes to your DCF assumptions knock 30% or more off the value.
• Everyone knows the story but few know the numbers. When people can explain why a company is exciting but not how much cash it produces, price has usually left fundamentals behind.

The sensitivity test

Here is a quick way to check whether a price depends on perfection. Take your valuation and trim growth slightly, lower the long-term margin a little, and raise the discount rate by one percentage point. If the value collapses, the stock is priced for perfection. A genuinely cheap stock still looks reasonable under modestly worse assumptions.

What Makes One Stock a Better Buy Than Another?

Investors often ask which of two good companies is the better buy. The answer usually comes down to price.

A better buy is the one that offers the higher expected return for the risk you take. Quality sets what a business can earn over time. The price you pay decides how much of that you actually capture.

That means a slightly less exceptional business at a much better price can be the better investment. It also means your favourite company can become a worse buy simply because its price has run ahead.

Worked Example: Company A vs Company B

Let’s compare two hypothetical businesses. Both pass the first four of the Five Criteria.

Measure	Company A	Company B
Return on invested capital	25%	18%
Expected FCF growth	10% a year	7% a year
Free cash flow per share	$2.00	$4.00
Share price	$100	$55
Free cash flow yield	2.0%	7.3%

Company A is the better business. It earns higher returns and grows faster. Many investors would buy it without looking twice.

Now use a simple approximation for long-run return: starting cash yield plus growth, assuming the valuation multiple stays flat. Company A offers roughly 2% plus 10%, or 12%, but only if its high multiple holds. Company B offers roughly 7.3% plus 7%, or about 14%, from a much lower starting multiple.

The bigger difference is the downside. If Company A’s growth slips to 6% and the market lowers its multiple, the return could fall to low single digits or below zero. Company B’s high starting yield gives it a cushion. It needs far less to go right.

On today’s prices, Company B is the better buy. If Company A fell to $60, the answer would flip. Price changes the answer.

Why Cheap Stocks Are Often Cheap for a Reason

Low multiples attract beginners, but the market is often right about troubled businesses. A stock can look cheap because:

• The industry is in structural decline and earnings will keep falling.
• A competitor is taking share and the moat is eroding.
• Debt is high and a refinancing is coming.
• Management is destroying value through poor acquisitions.
• Current earnings are at a cyclical peak and about to drop.

This is why the Five Criteria put price last. A stock trading at five times earnings that fails criteria 1 to 4 is not cheap. It is a value trap. Our guide to red flags in a business covers the warning signs.

Before buying anything that looks cheap, ask one question: why is it cheap, and why do I think the market is wrong? If you cannot answer both parts, keep looking.

When Should You Sell an Expensive Stock?

Recognising an expensive stock matters when you already own it. Three situations justify selling:

1. The thesis breaks. The moat weakens, management changes course badly, or the business structurally declines.
2. You find a clearly better use of the money. Another business passes all five criteria at a much larger margin of safety.
3. The price far exceeds a conservative estimate of value. Your expected return from here is poor even if the business keeps doing well.

Be careful with the third reason. Great businesses often grow into their valuations, and selling a wonderful compounder too early is a costly mistake of its own. Taxes and trading costs also argue for patience. My own default is to sell on valuation only when the price looks clearly extreme, not merely full.

How We Use This in the Five Criteria

Criterion 5 asks one question: does the price leave a margin of safety? The house default is that a stock passes if it has either:

• A free cash flow yield of 5% or more, or
• A price at least 25% below a conservative intrinsic value.

In practice, the four tests above feed that decision. The DCF gives you the intrinsic value. The cash yield gives you a quick check. History and peers tell you whether the market is unusually pessimistic, and whether you should look harder for a hidden problem.

Our margin of safety guide explains why the 25% discount matters and how to adjust it for less predictable businesses.

Common Mistakes When Judging Cheap vs Expensive

• Confusing a low share price with a cheap stock. The number of dollars per share tells you nothing without earnings and cash flow.
• Anchoring to the 52-week high. “It’s down 50%” is not an analysis. The old price may have been wildly too high.
• Using a single metric. A low P/E can hide heavy debt or poor cash conversion. Cross-check with price to free cash flow and the balance sheet.
• Assuming great businesses are always worth buying. Quality justifies a premium, not any premium.
• Ignoring why the market disagrees. If you cannot state the bear case, you have not finished your research.

Your Next Step

• Learn why paying too much is so damaging in the largest risk to your wallet: overpaying for stocks.
• Avoid the classic errors in valuation mistakes beginners make.
• Track stocks until they reach your price with a stock watchlist.

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About the author: Cameron Hayes is a senior investor relations and finance professional who has worked in IR at Nasdaq Copenhagen-listed companies including Nilfisk and Maersk Drilling. He holds an MSc from Copenhagen Business School and a BCom from the University of Ottawa, and founded Gingernomics to teach individual investors the Five Criteria framework. More about Gingernomics.

The content on Gingernomics is for educational and informational purposes only and does not constitute financial advice. Always do your own research and consult a licensed financial advisor before making any investment decisions. Past performance is not indicative of future results.