LONDON -- Each day this week, I'm looking at a master investor, introducing you to his or her approach and running a stock screen to unearth examples of the type of company that approach produces.

So far I've looked at Ben Graham, the pioneer of value investing, and Phil Fisher, an early growth guru. Today, it's the turn of the world's greatest living investor, Warren Buffett -- a.k.a. the Oracle of Omaha -- who has been influenced by both Graham and Fisher.

Reading the oracle
Millions of words have been written about Warren Buffett's approach to investing, including books by his former daughter-in-law, old colleague David Clark, and fund manager Robert Hagstrom.

Buffett himself has never written a book, but his annual shareholder letters to investors in his Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B) group are essential reading, providing many insights into his approach, even if they don't amount to a step-by-step guide to identifying a Buffett stock. In addition, Buffett has commended The Essays of Warren Buffett by Larry Cunningham as "a coherent rearrangement of ideas from my annual report letters."

Buffett's roots
Many years ago, Buffett said, "I'm 15% Fisher and 85% Benjamin Graham." What did he mean by that?

In common with Graham, Buffett is a big believer in having a "margin of safety," which means buying shares when they're trading below their true value -- typically when they're out of favor with Graham's fickle and impatient "Mr. Market." Buffett believes the margin-of-safety principle so strongly emphasized by Graham to be "the cornerstone of investment success."

From Fisher, Buffett learned the importance of strong management in a company and of what Fisher referred to as "management of unquestionable integrity." Also like Fisher, Buffett advocates investing with a long-term horizon: "If you aren't willing to own a stock for 10 years, don't even think about owning it for 10 minutes."

Buffett is in accord with Fisher on portfolio concentration, too, going so far as to say: "If you are a know-something investor, able to understand business economics and to find five to 10 sensibly priced companies that possess important long-term competitive advantages, conventional diversification makes no sense for you. It is apt simply to hurt your results and increase your risk."

Moats and cash
The idea of investing in companies with "important long-term competitive advantages" is quintessential Buffett. Companies with a big "economic moat," such as those with strong consumer brands -- Coca-Cola is a Buffett stock par excellence -- have good pricing power and give shareholders a high return on equity.

Buffett avoids industries he doesn't understand -- i.e., that are outside his "circle of competence" -- sticking to businesses that are "relatively simple and stable in character," not least because: "If a business is complex or subject to constant change, we're not smart enough to predict future cash flows."

Buffett is dismissive of common valuation yardsticks, such as price-to-earnings and price-to-book ratios and dividend yield, "except to the extent they provide clues to the amount and timing of cash flows into and from the business." Cash is king for Buffett -- especially a cash-flow measure he calls "owner earnings."

A Buffett screen
Buffett aficionados and apostles have come up with innumerable stock screens, using sophisticated combinations of financial-statement numbers and valuation metrics to try to capture the universe of stocks Buffett might consider investing in.

The futility of this is amply illustrated by the fact that Tesco (OTC: TSCDY), which Buffett recently purchased (the transaction is detailed in our special free report, "One UK Share Warren Buffett Loves"), didn't get flagged by any of the screens I used!

For a manageable list of companies for this article, I took the industries represented among Buffett's top holdings (excluding financials) as a starting point. I then screened the FTSE 350 for companies in these industries using just two criteria: an average annual return on equity of 15%-plus over five years and an average annual earnings growth of 10%-plus over ten years (the latter only in the absence of an owner-earnings facility on the screener).

Company

Market Cap (billions of pounds)

Share Price (pence)

Return on Equity

Earnings Growth

AG Barr 0.4 1,122 21% 14%
BG Group 43.3 1,275 20% 18%
BP (NYSE: BP) 76.2 400 17% 17%
Cranswick 0.4 826 16% 15%
Reckitt Benckiser 25 3,443 37% 18%
Smith & Nephew 5.4 595 21% 12%
Tesco 25.4 316 18% 12%
Unilever (NYSE: UL) 58.4 2,069 34% 17%

The FTSE 100 companies or their brands will certainly be familiar to many of you -- which is how it should be with a classic Buffett stock -- and at least my simple screen has flagged up Tesco!

Of the two smaller companies, I don't know too much about Cranswick -- maker of free-range, organic sausage -- having only briefly looked at the firm a year ago. But I do have AG Barr, the maker of IR-BRU, penned as a Buffett business.

Foolish bottom line
Buffett's approach to investing has perhaps been most succinctly summed up by the Oracle himself: "Your goal as an investor should simply be to purchase, at a rational price, a part interest in an easily understandable business whose earnings are virtually certain to be materially higher five, 10, and 20 years from now."

The master investor we'll be looking at tomorrow shares that view, having said that "a share in a stock is not a lottery ticket; it's part ownership of a business." Nonetheless, he has his own distinctive approach to investing.

David Kuo challenged his Motley Fool analysts to pinpoint the attractive sectors of 2012 -- and they delivered! Discover the industries they selected in this new Motley Fool guide -- "Top Sectors Of 2012" -- while it's still free!

Further investment opportunities: