Warren Buffett is the chairman and chief executive officer of Berkshire Hathaway. A long-time believer in value investing, Buffett, who is known as the "Oracle of Omaha," is consistently ranked as one of the wealthiest people in the world. For several years, Buffett, who is now 80 years old, and the Board at Berkshire Hathaway have made vague allusions to Buffett's successions plans. The lack of a clear plan has some investors on edge as they wonder who is going to be left driving the ship that has had such a successful voyage to date. (They don't call him "The Oracle" for nothing. Learn how Buffett comes up with his winning picks. See Think Like Warren Buffett.)

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Berkshire Hathaway has acknowledged that no one person can fill Buffett's shoes once he retires; rather, Buffett has said that Berkshire's investment duties are expected to be divided among three or more different managers who would report to a CEO. Rumors held that David Sokol, the chief executive of Berkshire Hathaway's NetJets airplane charter unit, was the prime candidate in the running to eventually replace Buffett as CEO of Berkshire Hathaway. On March 31, 2011, however, David Sokol resigned unexpectedly and is now currently being investigated for unethical trading practices. This event further antagonizes investors over the future fate of the company. Though the Board continues to be vague about succession plans, here is a look at the candidates that are expected to be contenders for Warren Buffett's CEO position.

Greg Abel, President and CEO of MidAmerican Energy
Greg Abel oversees MidAmerican Energy Holdings Company, a group of utilities and natural-gas pipelines and a real estate brokerage. MidAmerican earned combined revenues of $11.2 billion in 2010. Based in Des Moines, Iowa, Abel also sits on numerous boards.

Perhaps more important than his impressive resume is the fact that Buffett himself has praised Abel as a "brilliant manager" and a "huge asset" to Berkshire. At 48 years old, Abel is the youngest contender on the list, which might be a consideration if Buffett stays on the job for the next decade.

Ajit Jain, Berkshire's Reinsurance Division
Born in 1951, Jain oversees several reinsurance businesses for Berkshire Hathaway. Upon graduating Harvard Business School in 1978, he joined McKinsey & Co, a global management consulting firm. He left McKinsey in 1986 to join Buffett in insurance operations. The reinsurance business specializes in large risks, and the premiums it collects provides significant funding for Buffett's investments. Buffett has said that "Ajit has probably made a lot more money for Berkshire Hathaway than I have." Bloomberg has reported that Berkshire's board of directors would support Buffett's decision to select Jain as the next CEO, provided it was a position that Jain would accept. (The Oracle of Omaha's "Rip van Winkle" approach has served him well. Read on to learn more. Check out Warren Buffett's Best Buys.)

Tony Nicely, Chairman, President and CEO of GEICO
GEICO is an indirect, wholly owned subsidiary of Berkshire Hathaway. In 1993, Nicely was named GEICO's new chairman and now serves as the CEO. Nicely swiftly implemented a new strategy to expand GEICO's customer base and amplified its focus on advertising, resulting in increased national visibility. This caught Buffett's attention. In 1996, Warren Buffett purchased GEICO's outstanding stock, making it a subsidiary of Berkshire Hathaway. GEICO continued to grow, adding services and product lines, and today boasts for than 10 million policyholders with assets topping $28 billion. Buffett has said that "[Nicely] remains an owner's dream. Everything he does makes sense."

Matthew K. Rose, Chairman and CEO of Burlington Northern Santa Fe
Matthew K. Rose is one of the most recent managers to enter the Berkshire Hathaway family. Burlington Northern Santa Fe Corp, a major railroad, was purchased by Berkshire Hathaway in 2010. The $34 billion deal was Berkshire Hathaway's biggest acquisition to date. In his letter to shareholders, Buffett called the acquisition of BNSF "the highlight of 2010." Buffett wrote, "It now appears that owning this railroad will increase Berkshire's 'normal' earning power by nearly 40% pre-tax and by well over 30% after-tax." And later in the letter, "I am proud of what has been accomplished for our society by Matt Rose at BNSF… I am also both proud and grateful for what [he has] accomplished for Berkshire shareholders."

The Bottom Line
Despite acknowledging the need to define a succession plan, Buffett has no immediate plans to retire. As Buffett said, "It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you'll do things differently." Buffett has molded Berkshire Hathaway, turning it from a failing textile mill into the successful conglomerate holding company that it is today. He is not in a rush to hand over the reins. Eventually, however, Buffett and Berkshire Hathaway will likely split Buffett's duties into three parts: chief executive officer, chairman and several investment managers. Who will fill these posts is a question that investors and market watchers will endlessly churn over until the decisions are final. (We take a close look at the main principles the 'Oracle of Omaha' uses in assessing a company. Refer to What Is Warren Buffett's Investing Style?)