Rule of 40 Explained: Screen the Best Growth Stocks
What is the Rule of 40?
Would you rather own a company growing revenue 50% a year while losing money, or a profitable one growing at only 5%? Ask a room of investors and it splits down the middle, because neither number tells the whole story on its own. Fast growth can hide a business burning cash to buy it. Fat margins can hide a company that has stopped expanding.
The Rule of 40 was built to settle that argument in a single number. Add a company’s revenue growth rate to its profit margin: if the total clears 40, the business is holding a healthy balance between expansion and profitability. Forecaster has just added the Rule of 40, with the full history of the metric for every company and a way to rank any index by it. This guide explains what the ratio measures, why one good year is not enough, and how to read it inside the terminal.
The Rule of 40 is a health check for growth companies, most often software and SaaS businesses. The formula is deliberately simple:
Rule of 40 = revenue growth rate (%) + profit margin (%)
A score at or above 40 is the pass mark. The profit-margin side can be measured a few ways depending on the source: free cash flow margin, EBITDA margin, or operating margin are the common choices. Forecaster’s own definition leans on cash generation. The terminal’s info-box describes the ratio like this:
“Growth and profitability in a single number: how fast revenue is growing plus how much of that revenue turns into cash. A company can lean on either side — fast growth with thin margins, or slow growth with fat margins — and still score well.”
That last point is the useful part. Two very different companies can post the same Rule of 40. Company A grows revenue 45% but runs a −12% margin: its score is 33. Company B grows a modest 8% with a healthy 27% margin: its score is 35. On the Rule of 40, Company B edges ahead, even though Company A looks faster at first glance. The ratio forces growth and profitability onto the same scale so they can be compared directly.
Why the Rule of 40 matters
Revenue growth on its own is a dangerous number. A company can grow while destroying value, spending far more to win each new customer than that customer will ever return. The Rule of 40 exists because growth and profitability, read separately, each tell only half the story.
This matters most for young technology companies. A fast-growing software business is often unprofitable on paper for a reason: it is investing heavily in customer acquisition, product development, sales teams, international expansion, and cloud infrastructure. Judge it on net income alone and you would walk away from a strong business. Judge it on growth alone and you would ignore the cash it is torching. The Rule of 40 nets the two against each other, so a company losing money today can still register as high quality if its growth is large enough to justify the spend.
Palantir shows why the history matters more than the latest reading. Its annual score reached 61.94% in 2021, fell below the threshold to 33.25% in 2022, then recovered to 48.08% in 2023, 68.62% in 2024, and 103.12% in 2025. The current TTM reading is 130.13%. That progression is stronger evidence than the latest number alone: it shows both the interruption in 2022 and the acceleration that followed.
The framework behind Forecaster’s fundamental tools draws on the same school of thinking. Adam Seessel’s book Where the Money Is inspired the terminal’s Qualitative Scorecard inside the Financial AI Agent, which scores a business on durable quality rather than a single quarter. The Rule of 40 sits in that same fundamentals toolkit: a quick, numeric read on whether a growth story is actually paying its way.
One year isn't enough: the Bain study
Clearing 40 for a single year is easy to overrate. The more important question is whether a company can stay above the line, and here an often-cited study from Bain & Company is worth reporting as the webinar presented it.
Bain & Company analysed 124 publicly traded software companies. In its historical sample:
- 40% beat the Rule of 40 in a single year (2017).
- 25% sustained it for at least three years.
- Only 16% held it across all five years studied.
Bain also found that companies sitting above the Rule of 40 line traded at roughly twice the enterprise-value-to-revenue multiple of those below it. The takeaway is straightforward: passing the Rule of 40 once is not particularly impressive, but staying above 40 consistently is, and the market pays up for that consistency. A one-year snapshot can flatter a company that is about to fall back. The full history is what separates a durable compounder from a business having a good twelve months.
These figures come from the Bain & Company study cited in Forecaster’s webinar and are reported here as presented. The original Bain brief is linked above for source context.
That is exactly why a single score, pulled from one filing, is the wrong way to use the ratio, and why Forecaster shows the whole track record instead.
How to read the Rule of 40 in Forecaster
Inside the AI Trading Terminal, the Rule of 40 lives with the rest of a company’s fundamentals. Open any stock, go to Fundamentals → Ratios → Financial, and find the Rule of 40 row. Click it, and a pop-up opens with the complete history of the ratio for that company.
Two controls make the history useful:
- Annual / Quarterly toggle. Switch between full-year figures and a quarter-by-quarter view to see how the balance is trending, not just where it landed last year.
- TTM (trailing twelve months). TTM sums the last four reported quarters rather than relying on the most recent annual statement. It gives a near real-time read on the company, which matters when a business is inflecting fast.
Micron Technology is a good stress test for reading the chart properly. Its most recent Rule of 40 reads well above 200 on a TTM basis, an eye-catching number driven by a sharp upswing in the memory-chip cycle.
But look at the annual bars across the full history and the caution writes itself. Micron is a cyclical business: its Rule of 40 has swung from deeply negative in down-cycles to triple digits in up-cycles. A 219% score is real, but it is a peak-of-cycle number, not the steady, above-40 line that Palantir prints. This is the limit of the ratio, and the reason the history view exists. The Rule of 40 was designed for consistent growth businesses; on a cyclical, a single spike says more about where the cycle is than about the durability of the business. Read the whole chart, not the top bar.
Screen any index by the Rule of 40
The history chart answers “how good is this one company.” The Rankings page answers “which companies are best.” From Rankings, pick an index, open Ratios → Financial, and click the Rule of 40 column header to sort every component of that index by the metric. Forecaster covers the major global indexes, so the same workflow runs on the S&P 500, the NASDAQ, or the S&P MidCap 400.
In the Rankings snapshot reviewed on 29 July 2026, Strategy topped the NASDAQ list, followed by Micron, Palantir, NVIDIA, and AppLovin. The Rule of 40 did not drop below 40 until roughly the 46th company. These positions will change as new financial statements enter the calculation. The ranking is a fast way to build a shortlist of quality growth stocks; each candidate’s history then shows whether the score is consistent or a one-year flash.
A word of caution when you screen: the ratio was built for fast-growing software and technology companies. As with Micron, a cyclical stock can top the list for the wrong reason. Use the ranking to find candidates, then let the history chart do the real filtering. SoFi Technologies is a cleaner example of the signal the metric is meant to catch: its Rule of 40 has been turning positive on a TTM basis, a sign the growth-versus-profitability balance is improving in close to real time.
How the metric is built
Once you can see the two inputs, the score stops being a black box. Forecaster uses the cash-based version described in its info-box: revenue growth plus free cash flow margin. Other sources use EBITDA or operating margin, so two providers can show different Rule of 40 values for the same company. Compare companies with one definition and one reporting period.
Working through the two components by hand is worth doing once. It shows which side of the ratio is carrying the score, growth or cash generation, which is the difference between Company A and Company B in the opening example. It also makes the cyclical trap obvious. When a large Rule of 40 is built on a temporary surge in both inputs, treat it as a cycle reading rather than a quality verdict. Forecaster does the arithmetic and keeps the full annual and quarterly history so you can see whether those inputs are durable or fleeting.
Put the Rule of 40 to work
The Rule of 40 is not a buy signal on its own, and no single ratio should be. It is a filter that tells you, in one number, whether a growth company is expanding in a financially healthy way or buying its growth at any cost. Used with the full history and alongside the rest of Forecaster’s fundamental analysis, it is a fast, honest way to separate durable compounders from businesses having a good year. Open the AI Trading Terminal, find the Rule of 40 under any company’s ratios, and rank your favourite index by it.
Frequently asked questions
What is a good Rule of 40 score? A score at or above 40 is considered healthy: the sum of a company’s revenue growth rate and its profit margin clears the 40 mark. More important than a single reading is consistency. As the Bain study cited above shows, only 16% of the software companies sampled stayed above 40 across all five years, and those that did tended to earn roughly double the EV/revenue multiple of those below the line.
What is the Rule of 40 formula? Revenue growth rate (%) plus profit margin (%). The margin can be free cash flow margin, EBITDA margin, or operating margin depending on the source. Forecaster’s definition emphasises cash generation, “how much of that revenue turns into cash,” so free cash flow margin is a natural fit, though the metric works with any consistent margin definition.
Does the Rule of 40 work for every stock? No. It was designed for fast-growing software, SaaS, and technology companies, where a business may be temporarily unprofitable while it invests in growth. On cyclical companies such as memory-chip maker Micron, a single high score can reflect the peak of a cycle rather than durable quality, which is why reading the full history matters.
What does TTM mean for the Rule of 40? TTM stands for trailing twelve months. Instead of using the last annual statement, it sums a company’s four most recent quarters, giving a near real-time view of the ratio. It is especially useful for companies whose growth or margins are inflecting quickly, such as a business turning profitable for the first time.
Where do I find the Rule of 40 in Forecaster? For a single company, open it and go to Fundamentals → Ratios → Financial, then click the Rule of 40 row to see its full annual and quarterly history. To compare a whole market, use the Rankings page, choose an index, open Ratios → Financial, and sort by the Rule of 40 column. Browse the Forecaster tutorials for the in-terminal course on ratios and rankings.
About Forecaster
By the Forecaster Research Team. Forecaster builds an AI Trading Terminal that combines fundamental analysis, seasonality, sentiment, and a 24/7 Financial AI Agent. This guide is based on the fundamental-analysis tools our team develops and on the co-founder-led market webinar in which the Rule of 40 was introduced to the platform. For related fundamental features, see Moat Analysis and what the Forecaster terminal does.
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