If you're a busy investor with more than just stock-picking on your plate, you might want to consider a mechanical investing strategy. And if you're interested in stocks, one of the most intriguing of these strategies is Joel Greenblatt's Magic Formula.

Greenblatt details this approach in his enriching, funny The Little Book That Beats the Market. His strategy revolves around two factors:

  • How cheap is the stock?
  • How profitable is the company?

This simplified approach really boils down value investing to its essence. When you find a company whose price fails to reflect its high profits, you might have a winner.

A cheap business and a profitable company
To find cheap companies, the Magic Formula looks for a high earnings yield -- basically, a company's EBIT divided by its enterprise value. EBIT is earnings before interest and taxes, otherwise known as operating earnings. Enterprise value includes the company's market capitalization, then adds its net debt. In general, the higher the earnings yield, the better. The Magic Formula looks for a yield higher than 10%.

To find profitable companies, Greenblatt's Magic Formula seeks businesses that generate returns on assets greater than 25%. In other words, for every $100 in assets it holds, the company would produce at least $25 in net profit. In general, the higher the ROA, the better the business. Greenblatt looks for companies with an ROA higher than 25%.

So how do these pharma companies fare?

Company

Enterprise Value

EBIT

Earnings Yield

ROA

Johnson & Johnson (NYSE: JNJ) $146,827 $16,527 11.3% 10.5%
Eli Lilly & Co. (NYSE: LLY) $39,124 $6,772 17.3% 14.5%
Teva Pharmaceutical (Nasdaq: TEVA) $48,247 $4,406 9.1% 7.7%
Bristol-Myers Squibb (NYSE: BMY) $40,579 $6,268 15.4% 12.6%

Source: Capital IQ, a division of Standard & Poor's. Non-percentage numbers in millions. Trailing-12-month figures.

Going by the Magic Formula criteria, three companies meet the formula's earnings yield target of 10%, with Teva coming up just short. But for the ROA component, no company surpasses the 25% threshold. Eli Lilly tops this list at 14.5%. Sure, these companies didn't meet the high bars for the Magic Formula screen, but that certainly doesn't mean they can't be profitable investments. These high-quality companies are rarely on sale, and so they often won't make the Magic Formula cut.

Foolish bottom line
The key advantage of the Magic Formula is speedy decision-making. You can run a screen and mechanically buy the stocks, then spend your free time doing the activities you love. However, such an approach means that you need to pick a lot of stocks (say, 25 or 30), since you haven't performed any strategic analysis of your investments. According to the formula, you should hold the stocks for one year in order to receive favorable tax treatment, sell all of them, and then run the screen again to find your new picks.

While this approach sounds easy, Greenblatt cautions that it can be tough to stick with during hard times. In some years, this mechanical strategy simply won't work. However, Greenblatt's extensive backtesting suggests that over the long haul, his Magic Formula can significantly outperform the market.

Interested in Johnson & Johnson? Add it to My Watchlist, our free, personalized stock tracking service. You can also add Eli Lilly, Teva, or Bristol-Myers Squibb and get free Foolish content on these stocks and any others you like.

Jim Royal, Ph.D., owns shares of Johnson & Johnson. Johnson & Johnson is a Motley Fool Inside Value choice. Johnson & Johnson is a Motley Fool Income Investor recommendation. Motley Fool Options has recommended a diagonal call position on Johnson & Johnson. The Fool owns shares of Johnson & Johnson and Teva Pharmaceutical Industries. Motley Fool Alpha owns shares of Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.