How to Know If a Stock Is a Good Buy: A Working Checklist

You have a stock in mind. You have read a few things about it. You like the company. You think it might be a good buy at today's price. The next step — actually deciding — is where most retail investors stop doing real work and start clicking buttons. This guide is the missing checklist for how to know if a stock is a good buy. Five questions you have to answer yes to before you commit money. A concrete number to see at each one. A worked example using Starbucks at $99 so you can see what the verdict looks like on a stock people are actively wondering about right now.

The reason most articles on how to know if a stock is a good buy are useless is that they list metrics without thresholds. They tell you to "look at the P/E ratio". They never tell you below what number is a good buy on P/E. They tell you to "check the dividend". They never tell you what dividend yield is meaningful. The fix is not more metrics. The fix is a small number of well-chosen ones, each with a specific cut-off, applied in a specific order. That is what this checklist does.

Two warnings before we start. First, the checklist tells you whether a stock is a good buy at today's price. It does not tell you whether the stock will be a good buy next month at a different price. Second, the checklist's job is to make you state your assumptions out loud. A critic can then argue with them. The whole exercise is more valuable as a discipline than as a tool that produces buy or pass answers automatically.

What "good buy" actually means (and what knowing how to know if a stock is a good buy depends on)

Three distinctions retail investors get wrong constantly. Knowing how to know if a stock is a good buy starts with not confusing these three things:

• "Good buy" is not "stock will go up next month". Markets misprice stocks for years. A stock can be a good buy today and still be down twelve months from now. The checklist tells you whether the price is defensibly low, not whether anyone else has noticed yet.
• "Good buy" is not "good company". A great business at the wrong price is not a good buy. Some of the most overvalued stocks in any given year are the most beloved companies. The checklist forces you to distinguish "I admire this business" from "I should own this business at this price".
• "Good buy" is not "everyone is talking about it". A popular discussion topic on Reddit, Twitter, or financial news carries approximately zero signal about whether the stock is a good buy. Often it is a slightly negative signal. By the time retail attention concentrates, the easy mispricing has already been arbitraged.

What "good buy" does mean: at today's price, you have a defensible reason to believe the business is worth more than the market is paying. The margin between those two has to be big enough to absorb your forecasting error and still leave a meaningful return.

The 5-question checklist for how to know if a stock is a good buy

The full checklist is below. Each question has a concrete pass/fail threshold. You unpack each question in the sections that follow, then run the whole thing on Starbucks.

1. Is this a business you understand? Threshold: you can explain how it makes money in two sentences without using the word "synergies".
2. Are the numbers healthy on their own? Five financial signatures: revenue 5-year CAGR ≥3%, operating margin stable or expanding, ROIC ≥15%, FCF yield > Treasury + 2%, net debt/EBITDA < 3x. Need at least four of five.
3. Does the business have a moat? Threshold: you can name an intangible asset, switching cost, network effect, cost advantage, or efficient-scale moat that survives 10 years of competition — and verify it in the gross margin trajectory.
4. Is the price meaningfully below intrinsic value? Threshold: a defensible IV calculation produces a per-share number at least 30% above today's price.
5. What would change your mind? Threshold: you can name two specific things that, if they happened, would invalidate the thesis. Write them down.

Need at least yes to all five for a clear good buy. Yes to three or four with named specific risks is a smaller, conviction-weighted position. Anything less is a pass.

Question 1 — Is this a business you understand?

The single most underrated filter when learning how to know if a stock is a good buy. The test is simple and surprisingly hard to pass:

Without looking anything up, can you explain in two sentences (a) what the company sells, to whom, and (b) how it makes money on each sale?

If you can, proceed. If you cannot, you are not yet equipped to evaluate whether this stock is a good buy. Read Item 1 of the company's 10-K — the "Business" section — and try again. After fifteen minutes, if it still doesn't fit in two sentences, pass. The number of US-listed businesses you will never fully understand is large. You are under no obligation to own any of them.

Industry experience helps but is not required. What matters is that you have a clear-enough mental model of the business to interpret its financials. A regional bank, a semiconductor designer, and a pharmaceutical company all have radically different cash-flow profiles for very different reasons. If you can't tell which of those you are looking at, you cannot read the numbers correctly.

Question 2 — Are the numbers healthy on their own?

This is the question most articles on how to know if a stock is a good buy gesture at and then fail to answer with specifics. Question 2 in our how to know if a stock is a good buy checklist gets numeric. The numbers you check are these five, each with a concrete threshold:

Revenue growth (5-year CAGR). Pull annual revenue for each of the last five fiscal years. Compute the compound annual growth rate. Threshold: ≥3% for a mature business; ≥10% for a growth business. Below 3% on a five-year horizon usually means the business is shrinking in real terms after inflation.

Operating margin trajectory. Operating income divided by revenue, for each of the last five years. What matters is the direction, not the absolute number. Expanding = pricing power or operating leverage. Compressing = competition winning or costs running ahead.

Return on invested capital (ROIC). NOPAT divided by debt + equity less excess cash. Threshold: ≥15% sustained over a full cycle. Below 10% means the business is barely earning its cost of capital — competition is doing what competition does.

Free cash flow yield. Free cash flow (OCF − capex) divided by market cap. Threshold: at least 2 percentage points above the 10-year US Treasury yield. With Treasury at ~4.5%, want ≥6.5% for a quality business at a fair price.

Net debt / EBITDA. Long-term debt minus cash, divided by trailing 12-month EBITDA. Threshold: < 3x for most businesses. Above 4x = meaningfully leveraged equity that is much more sensitive to operating disappointment.

Pass the question if at least four of five signatures clear their threshold. Three or fewer = the business is fundamentally challenged. You can still own it, but you need a concrete recovery thesis (Question 5), not optimism.

Question 3 — Does the business have a moat?

A moat is the structural reason the business will still earn above its cost of capital in ten years. Without one, your IV calculation in Question 4 is wishful thinking — competition arbitrages the returns away within a decade and any DCF or Gordon-growth model implodes.

The five legitimate moat types — intangible assets, switching costs, network effect, cost advantage, efficient scale — and how to verify each one in the financial statements are covered in detail in our economic moat guide. Read the section on financial signatures: sustained ROIC above 15%, stable or expanding gross margin, low capital intensity. If you can point to a moat type AND confirm it in the numbers, pass. If not, pass on the stock.

Question 4 — Is the price meaningfully below intrinsic value?

A business worth owning at any price is not the same as a business worth owning at today's price. Question 4 is the most important step in how to know if a stock is a good buy: it connects the two. The simplest defensible intrinsic value calculation is owner earnings × Gordon growth:

IV per share = Owner earnings per share × (1 + g) / (r − g)

Owner earnings is roughly net income plus depreciation and amortisation, minus maintenance capex — Buffett's correction to GAAP, walked through with worked examples in our owner earnings formula guide. Pick a discount rate (typically 8-10% for a quality business) and a long-run growth rate (2-4% for mature businesses, capped by long-run nominal GDP).

For more rigour, build a two-stage DCF — five years of explicit cash-flow forecasts plus a terminal value. The full worked walk-through is in our DCF valuation guide.

Once you have a defensible IV per share, compare it to the current price. A yes on Question 4 requires the IV to be at least 30% above today's price. That is the margin of safety — the buffer that protects you when your inputs turn out to be wrong. They usually do, at the margin. Full coverage of the margin of safety formula is in our margin of safety walk-through.

Question 5 — What would change your mind?

This is the question that separates real investors from people who own stocks for a while. The test:

Write down two specific things that, if they happened, would invalidate your thesis on this stock.

Generic answers ("a recession", "the market crashes") do not count. The answers have to be specific to this business. If gross margin drops below X. If management makes acquisitions of more than Y. If the new product line fails to reach Z by date W. Specific. Verifiable. Pre-committed.

If you can name two such things, pass. If you can't, you don't have a thesis — you have an opinion you have not stressed yet. The number of retail positions that have lost money because nobody wrote down the failure conditions in advance is uncountable. The discipline of writing them down before you buy is the difference between an analytical position and an emotional one.

This is also the question with the highest correlation to long-term returns. Investors who pre-mortem their positions outperform investors who do not, because they exit faster when the thesis breaks.

A worked example: how to know if a stock is a good buy on Starbucks at $99

Let's run all five questions on a stock retail investors are actively wondering about — Starbucks (ticker: SBUX), down from its 2021 highs and undergoing a strategic reset under a new CEO. Numbers from SBUX's fiscal-year 2025 10-K (year ended September 28, 2025), filed November 14, 2025.¹

Line item (SBUX FY2025)	Value
Revenue	$37.18B
Operating income	$2.94B
Net income	$1.86B
Cash from operating activities	$4.75B
Capital expenditures	$2.31B
Free cash flow	$2.44B
Long-term debt	$14.58B
Common shares outstanding (diluted)	1.143B
Share price at time of writing	$99.16
Implied market cap	~$113.4B

Question 1 — Business you understand. Starbucks operates company-owned and licensed coffee stores globally and sells coffee and food items at premium prices justified by brand and convenience. Two sentences. Pass.

Question 2 — Numbers healthy on their own. Computing the five signatures:

• Revenue 5-year CAGR: roughly 5% (revenue grew from ~$26B in FY2020 to $37.18B FY2025). Above 3% threshold. Pass.
• Operating margin: FY2025 op margin is $2.94B ÷ $37.18B = 7.9%. Historical SBUX op margin has been 15-17%. Trajectory is materially compressed. Fail.
• ROIC: NOPAT ≈ $2.94B × (1 − 0.21) = $2.32B; invested capital is complicated by negative book equity (heavy historical buybacks); using debt + adjusted equity as a proxy, roughly 15-17%. Pass, marginally.
• FCF yield: $2.44B ÷ $113.4B = 2.15%. Well below the 4.5% Treasury yield, much less Treasury + 2%. Fail.
• Net debt / EBITDA: $14.58B LT debt against FY2025 EBITDA ≈ $4.6B → ~3.0x. At the edge of the 3x ceiling. Marginal pass.

Three of five clear, two fail. Not a slam-dunk yes. The two failing signatures (compressed margins and low FCF yield) are exactly the failures the turnaround thesis aims to fix.

Question 3 — Moat. Starbucks has an intangible-asset moat (brand) and partial cost-advantage (scale in coffee supply chain, real estate negotiating leverage). The financial signature of the moat — the historical 15-17% operating margin — has clearly weakened. The moat is intact in narrative but not currently visible in the operating numbers. Marginal pass — moat exists, but is not earning its premium today.

Question 4 — Price below intrinsic value. Owner earnings per share: NI $1.86B + D&A $1.68B − maintenance capex (~70% × $2.31B) = $1.86B + $1.68B − $1.62B ≈ $1.92B, or $1.68 per share. Gordon growth at r = 10%, g = 3% (modest — recovery uncertainty): IV per share = $1.68 × 1.03 / 0.07 ≈ $24.72. At today's $99.16, the calculated IV is roughly one quarter of the market price. Fail by a wide margin on current owner earnings.

The kinder reading: if recovery normalises Starbucks earnings back toward FY2021-2022 levels (operating margin ~15%, NI ~$4.5B), IV at the same r and g jumps to roughly $60-70 per share — still well below $99. To justify the current price on this framework, you have to assume both margin recovery and meaningful continued growth that pushes earnings well above peak levels.

Question 5 — What would change your mind? The recovery thesis can be stated as two specific tests. First, comparable store sales growth turns positive in the US within 18 months. Second, operating margin returns above 12% within 36 months. If either fails, the thesis breaks. Pass on the discipline check.

Verdict. Starbucks is not a good buy at $99 on the strict checklist. Question 2 fails on two of five signatures. Question 4 fails by a wide margin even under generous recovery assumptions. The trade that exists is a recovery bet: you are paying $99 for an option on the new management team executing a credible turnaround over three to five years. That bet is defensible for someone with a high tolerance for the named risks in Question 5 and a small position size. It is not the same thing as the stock being a good buy in the methodology this checklist defines.

## Five things that do NOT tell you how to know if a stock is a good buy

The errors retail investors make in deciding how to know if a stock is a good buy are predictable. If you catch yourself relying on any of these, the right move is to stop and run the actual checklist instead.

1. The stock chart. Up and to the right is not "good buy". Down and to the right is not "buy the dip". The chart tells you nothing about whether today's price is below the intrinsic value of the underlying business.
2. "Buffett owns it". Buffett's cost basis is often public; you are almost never buying at his price. A stock that was a good buy at $50 in 2018 may not be one at $130 today.
3. "It has a 4% dividend yield". A dividend yield is a function of price and dividend. A 4% yield from a business that has just cut earnings 30% means the dividend is the next thing to go. Yield is not value.
4. "The CEO is famous". Brand-name management is not a moat and not a thesis. The 7-step research workflow tests management on capital allocation and skin-in-the-game, not on charisma.
5. "Everyone on Reddit/X/Substack is talking about it". Social attention is approximately zero signal about whether the price is below intrinsic value. By the time retail attention concentrates on a name, the obvious mispricing is usually gone.

How to know if a stock is a good buy the lazy way

The five-question checklist is sound and it works. It also takes about forty-five minutes per ticker once you have done it twice. If you want the same checklist applied to any US-listed stock, computed from live SEC filings and current market data, written up as a thesis you can read in five minutes — that is what our AI agent does. Enter a ticker; receive the same kind of worked checklist you just read above on demand. Try a name from your watchlist — start at the homepage and pick a ticker.

For the simpler entry-point version of this idea, our how to find undervalued stocks guide runs a five-signal screen. For the more rigorous full version of each question's underlying method, see how to research a stock before buying, the 10-K guide, the owner earnings formula, DCF valuation, the economic moat walk-through, and the margin of safety formula.

What disciplined stock-picking actually looks like

Most retail investors who lose money do not lose it because the math is hard. They lose it because they buy without ever running the checklist, or because they convince themselves the question they didn't answer was the one that didn't matter. The five questions are not a substitute for judgement. They are the discipline that makes judgement possible — they force you to state the assumptions you would otherwise leave implicit, and they let you audit the trade six months later when the price has moved for reasons you did not predict.

Knowing how to know if a stock is a good buy is, ultimately, knowing what you are willing to be wrong about. The investor who has written down the specific failure conditions on every position they own is going to make better decisions over a decade than the investor with the better-sounding theses. Discipline is the moat. That is the real answer to how to know if a stock is a good buy: keep the discipline, write the thesis down, name the failure conditions, and only buy when the checklist says yes.

For more long-form essays on value-investing methodology, see the [rest of the Hub](/hub).