Eat your heart out Warren Buffett. Carlos Slim is the world's richest man, and the Wall Street Journal took a fascinating look at his investment secrets in the weekend edition. According to the piece:

It's hard to spend a day in Mexico and not put money in his pocket. The 67-year-old tycoon controls more than 200 companies -- he says he's "lost count" -- in telecommunications, cigarettes, construction, mining, bicycles, soft drinks, airlines, hotels, railways, banking, and printing. In all, his companies account for more than a third of the total value of Mexico's leading stock market index, while his fortune represents 7% of the country's annual economic output.

His secret? Monopolies. He has a stranglehold on the telephone industry in Mexico, and has drawn the inevitable comparisons to the robber barons of the early industrial days of the United States. While I lack the time or the familiarity with Slim's career to opine on the ethics of his maneuvers, I do note an interesting similarity between Warren Buffett, Bill Gates, and Carlos Slim, the world's three richest men: Gates built his fortune by creating a product that everyone needed and has many monopolistic qualities. Buffett built his by buying brands with "strong moats" at reasonable prices. Slim has sought to eliminate competition in the industries he operates in.

All three sought moats in some way, and seeking a moat is arguably the way to make money: If you're a worker, develop a valuable skill that other people don't have. That's a monopoly. Anytime you have something that other people want and can't get without you, that's a moat/monopoly.