Joel Greenblatt's Magic Formula: The Recipe, the Math, and the Blind Spots

In 2005, a hedge fund manager published a small book with a provocative title: The Little Book That Beats the Market. In it, Joel Greenblatt distilled three decades of practice into a single mechanical rule, simple enough for a teenager to run, serious enough to rest on the two most durable ideas in finance.

He called it the Magic Formula. The name is a deliberate joke: there is no magic, only the disciplined addition of two rankings.

Two questions, and nothing else

The whole formula fits in two questions asked of every company in a universe.

• Is the stock cheap? Measured by earnings yield: operating profit over enterprise value, that is EBIT ÷ (market cap + net debt). It is the inverse of EV/EBIT. The higher it is, the less you pay for each dollar of operating profit.
• Is the business good? Measured by return on capital: operating profit over the capital actually used to produce it, net fixed assets plus working capital. It is a close cousin of ROIC. The higher it is, the more the business turns a dollar tied up into profit.

Greenblatt ranks the entire universe on each question, adds the two ranks, and buys the best combined scores. A stock first on price but mediocre on quality, or the reverse, never wins: only the sum of the two counts.

Why these two, and no others

The choice is not arbitrary. It is the exact numerical translation of the synthesis Graham and Buffett spent a lifetime forming. Graham wanted to pay little: that is earnings yield. Buffett wanted profitable businesses that compound: that is return on capital. The Magic Formula is where the two meet, stripped to their barest form.

Earnings yield alone hands you cheap companies, many of them cheap for good reason. Return on capital alone hands you excellent companies, often already expensive. Together, they hunt the market's blind spot: a good business nobody is paying full quality price for.

A worked example

Take two companies in the same universe.

Illustrative figures, shown to demonstrate the ranking.

In a universe of just these two, A ranks first on both: cheaper and more profitable at once. Its combined rank is better, and it is the one the formula keeps. That is the easy case. The interesting case is when a company wins one ranking and loses the other, where adding the ranks decides, and where the trouble hides too.

What Greenblatt required around the formula

The book does not sell a number, it sells a discipline, and it matters as much as the math.

• A basket, not a single pick. You buy twenty to thirty of the best-ranked names, never one. The formula is right on average and across the basket, never guaranteed on a single line.
• Hold about a year, then rotate. Each position is held roughly a year, then replaced by the new list.
• Exclude financials and utilities. Their balance sheets make EBIT and capital employed hard to compare with the rest.
• Sit through the drawdown. Greenblatt insists: the formula underperforms regularly, sometimes for two or three years running. It is precisely because it is uncomfortable that it is not arbitraged away. Abandon it at the bottom and you collect the discomfort without the reward.

That last line is the real difficulty. The formula is trivial to compute and punishing to follow.

The blind spots

This is where most write-ups stop, and where a serious reader must keep going.

1. A single year's operating profit

The EBIT used is the latest year's. On a cyclical business, that figure lies: at the top of the cycle, profit is inflated and the yield looks wonderful right before it collapses. The formula loves cyclicals at the worst moment, the same trap the piece on value traps describes.

2. Balance-sheet blindness

The formula looks at neither debt, nor cash, nor the ability to survive a bad year. A highly profitable, highly leveraged company screens beautifully until the debt kills it. Earnings yield does use enterprise value, debt included, but nothing measures soundness: not a Piotroski F-Score, not an Altman Z-Score.

3. Accounting quality

EBIT is an accounting number, and an accounting number can be managed. Released provisions, capitalized costs, disposals dressed up as operations: none of it shows in the two ranks.

4. The small-cap bias

The formula's best historical returns come mostly from smaller, less-covered, less-liquid names. What reads well in a backtest runs, in practice, into costs and the impossibility of buying in size.

Where it meets what we do, and where it parts ways

The Magic Formula and our method start from the same two ideas: cheapness and the quality of capital. Our two closest readings descend straight from them, price on the EV/EBIT side, and profitability on the ROIC side.

The divergence is one of method, and it is deliberate. Greenblatt adds; we refuse to sum. Folding price and quality into one rank lets a good score quietly cover a bad one, exactly what the Rule of Two forbids. Health asks whether the business can hold up, Upside whether the stock has room to rise, Odds relates that upside to the risk of loss, and none of these readings is allowed to answer for another. A company brilliant on price but fragile on soundness does not show up in a sum; it shows up when the two readings sit side by side.

That is also why soundness, absent from the formula, is a reading in its own right for us: the bottom decile of Health puts a company on The Avoid List and keeps it out of The Sweet Spot, whatever its price says. What we publish is the rule, what puts a stock on a list and what takes it off, set out in full on the method page, and rebuilt every trading day in the ranking.

The Magic Formula remains what it always was: the shortest proof that a good investment fits in two questions. Its clarity is an enormous virtue. It lacks only a third question: will the business survive long enough for the other two to matter.

This article is information and education. It is not personalized investment advice. Investing carries a risk of capital loss.