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 pre-tax returns on assets (ROA) 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 some of the biggest marine companies fare?

Company

Enterprise Value

EBIT

Earnings Yield

ROA

DryShips $5,979 $295 4.9% 3.4%
Diana Shipping $696 $123 17.7% 7.8%
Genco Shipping & Trading $1,996 $148 7.4% 4.7%
Navios Maritime Holdings $1,785 $161 9.0% 5.5%
Seaspan $4,057 $255 6.3% 4.7%
Kirby $4,542 $312 6.9% 7.6%
Alexander & Baldwin $2,559 $109 4.3% 4.3%
Costamare $2,435 $157 6.5% 7.9%
Safe Bulkers $914 $111 12.1% 13.3%
Danaos $3,820 $189 4.9% 4.9%

Source: S&P Capital IQ.

Going by the Magic Formula criteria, none of these companies meets both standards. None of the companies offers the formula's desired 25% ROA and only two companies, Diana Shipping (NYSE: DSX) and Safe Bulkers, offer the formula's desired 10% earnings yield.

Many of these companies are suffering from a tough economic environment for dry bulk shipping due to shrinking demand, an oversupply of cargo shippers, and an inability to gain access to credit. Diana Shipping, for example, has suffered from an 11.5% decline in its average daily charter rate. Diana vessels recently ended a charter contract with one of BHP Billiton's subsidiaries for use of one of its vessels, which charged the company $52,000 per day to use it. The new contract only charges $14,000 per day -- a price reduction of more than 70%. Navios Maritime Holdings (NYSE: NM) has also suffered a decline in its average daily charter rate, but its decline is more modest.

Diana, like other companies in this industry, is finding it difficult to bring in the long-term contracts that lock in higher charter rates. While DryShips (Nasdaq: DRYS) has managed to lock in contracts that take up 54% of its dry-bulk capacity at an average rate of about $35,000 per day for 2012, even its advantage may dry up as those contracts expire unless things improve in the industry.

Genco (NYSE: GNK) has exhibited remarkable resilience in this rough time. Even though its average daily charter rate is currently a low $16,447, the company has still delivered an impressive profit in the most recent quarter. If it can maintain profitability during this difficult time, it may weather the storm of this difficult time for the industry and develop a stronger competitive position when things get better.

While most of the companies fail to offer a dividend, Seaspan (NYSE: SSW) currently offers an attractive 5.3% dividend yield. Like DryShips, Seaspan has managed to lock in long-term contracts that have insulated it from the oversupply and shrinking demand problems faced by the dry bulk shipping industry. In fact, the company already has contracts for ships it is currently in the process of building.

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.

One of the things that makes dividend income attractive is their predictability in volatile markets. While the dividends offered by Seaspan are high, it won't necessarily offer investors the stable income they are looking for. If you'd like to learn more about how you can get more predictable dividend payments at attractive yields, check out our free report, "Secure Your Future With 11 Rock-Solid Dividend Stocks." It's available free for a limited time. Just click here to get your copy.