OMAHA, Neb. — Last month, Warren Buffett posted the mother of all help-wanted ads: a request for candidates to replace him as chief investment officer of Berkshire Hathaway Inc.Now, the resumes are flooding in — and the process is turning out to be every bit as unconventional as the billionaire investor himself. Among the 600 or so applicants so far: a Talmudic scholar who picks stocks from home, a Canadian economist with an intense yoga practice and even a four-year-old.

“We’re going to run this like ‘American Idol’ in the end,” the 76-year-old Mr. Buffett quipped in an interview in his modest office, neatly decorated with baseball paraphernalia and photos of old friends. On a recent Sunday, he went in after lunch to read annual reports and open mail, some of which is destined for a small box on his desk labelled “TOO HARD.”

For all Mr. Buffett’s whimsy, it’s an important quest, both for his company, which has a market value of about $168 billion, and for his legions of fans. For decades, Mr. Buffett’s financial decisions have been the subject of conjecture, scrutiny and imitation. So, even though Mr. Buffett says he is in “excellent health” and has no plans to retire soon, the naming of a CIO successor signals for many the end of an era and a step into uncharted territory.

It won’t be easy to fill Mr. Buffett’s size 10-[1/2] shoes. Thanks largely to his legendary stock picking, the “Oracle of Omaha” is now the world’s second-richest man, topped only by Microsoft Corp.’s Bill Gates. An investor who bought $1,000 of Berkshire Hathaway Class A stock in 1965, after Mr. Buffett took control, would be worth more than $7 million today.

It takes “a peculiar temperament” to be an investor who consistently seeks opportunities away from the crowd, says Charlie Munger, Berkshire’s 83-year-old vice chairman. Mr. Buffett says Mr. Munger, whom he has known for more than four decades, would be the “ideal person” for the job — if he were just 30 years younger.

In his March 1 annual letter to Berkshire shareholders, Mr. Buffett laid out the virtues that he is seeking, such as “independent thinking, emotional stability, and a keen understanding of both human and institutional behaviour”.

Since 1965, Mr. Buffett has played the dual roles of CIO and chief executive of Berkshire, his holding company. Currently, Mr. Buffett manages the bulk of Berkshire’s roughly $120 billion portfolio of stocks, bonds and derivatives, which includes big stakes in blue chips such as Coca-Cola Co. and American Express Co. Berkshire also owns a stable of companies outright, including International Dairy Queen Inc., auto insurer Geico, utility MidAmerican Energy Holdings Co. and reinsurer General Re.

The new CIO will focus on securities investments and leave the bigger-picture decisions to Mr. Buffett’s successor as CEO. In March of 2006, Mr. Buffett announced that the board had identified three candidates for that higher-profile job. Those people, who weren’t publicly named, were chosen from among the dozens of managers overseeing Berkshire’s subsidiaries.

The search for successors appears to reflect a larger effort by an aging patriarch to get his house in order. In June, Mr. Buffett pledged 85 percent of his Berkshire stake, or about $44 billion at the company’s current stock price, to the Bill & Melinda Gates Foundation and four smaller charities. He said he would also leave the rest of his money to charity. Last August, he remarried on his birthday.

His emotions are sometimes near the surface. In his office, Mr. Buffett wiped away tears from behind his glasses while watching a video of investment manager William Ruane, speaking in 2003 about his efforts to clean up parts of New York’s Harlem neighbourhood. Mr. Ruane, a classmate of Mr. Buffett’s at Columbia University, rang up impressive gains at the Sequoia Fund for nearly 40 years.

“Now, wouldn’t you trust this man to manage your money?” he asked while gesturing to the image of his old friend, who died in 2005 at age 79. “I’m looking for another Bill Ruane,” he says.

Berkshire’s new candidate won’t be among Mr. Buffett’s longtime associates. He will have little to judge them on but their words, personal and private investment records — and his gut reaction to them. Mr. Buffett says he is confident that he will find one, and maybe two successful candidates. Famous for buying companies after brief meetings with owners, Mr. Buffett prides himself on being able to read strangers quickly. Pointing to three crates of laminated folders, scrawled notes and coloured envelopes bearing the hopes of hundreds of aspirants, he says: “There’s one in there.”

With Mr. Munger’s help, Mr. Buffett will whittle down the current contenders to about 20 “real possibilities”, he says, adding that he’ll start reading the letters in earnest after Berkshire’s annual shareholders’ meeting next weekend. From those 20, he will ask for personal investment records going back at least ten years. Then, after determining whether “the general attitude toward purchase and sale of securities is compatible” with Berkshire, he will fill the job with either one or two people. He plans to hand them up to $10 billion to manage until it is time for them to take over the entire portfolio.

Mr. Buffett explains that the purpose of the trial run is “to see if their decision-making apparatus works out, hopefully while I’m still alive.”

What it isn’t, however, is a mentorship programme, something many applicants have misinterpreted. He says he isn’t looking for someone to teach, but “for someone who already knows how to do it.”

The misunderstanding is reflected in dozens of letters from students, professional investors and a surprising number of engineers and lawyers hoping to be apprenticed to the master. “I assure you,” wrote one 20-year-old college student, “although I may be short on experience, I am very long on potential.” A lawyer in Oregon recommended his four-year-old son, characterising the toddler as a “great negotiator” on issues such as “bedtime, chores, allowance, baths, etc.”

Professional headhunters are sceptical about Mr. Buffett’s search. Some warn that his requirement of seeing candidates’ personal investment records could repel those who would rather be judged by their public track records.

“I’m sure he’ll come up against at least one person who says they aren’t comfortable doing that,” says Lawrence Lieberman of Orion Group, a New York firm that recruits managers for investment funds.

Indeed, notably absent from the application letters are some big-name money managers who have publicly expressed their admiration for Mr. Buffett. There’s no word from Edward S. Lampert, the 44-year-old chairman of Sears Holdings Corp. and head of Connecticut-based hedge fund ESL Investments Inc. Mr. Lampert declined to comment.

Nor does Thomas Gayner, chief investment officer of Markel Corp., a speciality insurer based in Richmond, Virginia, profess to be a candidate. Mr. Gayner, 45, manages Markel’s $1.7 billion stock portfolio with a bias toward long-term, concentrated holdings — a style favoured by Mr. Buffett.

He hasn’t applied, but three of his supporters sent letters to Mr. Buffett on his behalf. “It’s very flattering and very kind, but I’m trying to keep the job I have now,” says Mr. Gayner, whose appointment this year to the board of Washington Post Co., where Mr. Buffett has been a long-time director, gives him face-time with the Berkshire chairman.

Mr. Buffett acknowledges that some people, particularly some who know him personally, are too shy or embarrassed to apply. He says he might reach out to some of them eventually.

Many others, though, did put up their hands. The letters, reviewed by The Wall Street Journal, show a cross-section of Mr. Buffett’s devotees. Nearly all claim to have modest tastes and simple lives, mirroring Mr. Buffett’s. And, like him, they take pride in being unconventional, even at the risk of seeming idiosyncratic.

Take Joseph Weiss, a 40-year-old manager of a $7 million stock fund, who works mainly out of a basement office in his 2,000-square-foot red-brick home in the middle-class Brooklyn, New York, neighbourhood of Midwood. “I give you a somewhat virgin mind, although it has been quietly promiscuous,” he wrote in his letter. He was referring to his lack of a conventional college education, something Mr. Buffett says doesn’t impress him and isn’t a requirement for the CIO job.

Instead, Mr. Weiss holds two degrees in the study of the Talmud, ancient Hebrew texts on the laws of Moses. Sitting in his bright, sparsely furnished house on a recent morning after sending his five children to school — his wife works in Newark, New Jersey — the wiry, youthful-looking Mr. Weiss explained that his Talmudic education helps him “conceptualise and organise things”.

Mr. Weiss recounted a few investment successes, such as DeBeers, the diamond company, whose shares he bought in 1998 after figuring it was being valued in the stock market at far below the value of its diamond reserves.

In suburban Bannockburn, Illinois., David Steinberg was inspired to apply because of Mr. Buffett’s uncanny ability to make investment decisions based on his anticipation of changes in industries and the economy.

“I like his deep, forward-thinking wisdom,” says Mr. Steinberg, who manages about $200 million, mainly for wealthy clients in his DLS Capital Management fund. “He’s out in Omaha figuring things out that people will figure out on Wall Street 20 years later.”

Unlike many applicants who only have experience in managing stocks, the 41-year-old Mr. Steinberg has occasionally ventured into other investments. He bought “junk” bonds in 1990 and 2002 and invested in some troubled companies during their restructuring.

In Ottawa, economist Klaus Kostenbauer takes a more spiritual approach. As manager of Prosperous Yogi Investments, he regularly practices a rigorous form of yoga called kundalini, and meditates several hours a week.

“My yoga makes me a better investor,” says Mr. Kostenbauer, 40. “It helps with discipline, mastery of your emotions, and mastery of greed, fear and patience.” In his application letter, he jokingly offered to consult with Mr. Buffett in the afterlife through a Ouija board before making any investment decisions.

Mr. Buffett’s call for an independent thinker spoke to Mr. Kostenbauer. He avoids buying stocks owned by Berkshire unless he has done the research and understands them himself, setting him apart from many so-called Buffetteers. Since 1999, when he started managing about $10,000 of his own money as part of a local investing club, he has increased his holdings to $130,000, he says, by applying the value-investing principles of Benjamin Graham, a Columbia professor who became Mr. Buffett’s mentor.

Starting out with a small portfolio generally isn’t a deterrent to Mr. Buffett. When he met Mr. Munger in 1959, “I felt he could manage the largest portfolio in the world,” he says. At the time, Mr. Munger was a young corporate lawyer who didn’t manage any money.

Practically none of the letters mention pay. Some offered to work for free. “I’m already rich,” wrote one 49-year-old applicant in New Hampshire who enclosed a photo of himself. “Therefore, a salary of $0.00 a year would suit me just fine, and $1.00 a year would be excessive.”

Mohnish Pabrai, a hedge-fund manager in Irvine, California, who manages about $500 million in assets, says that working at Berkshire would be a “call to duty”.

“For me, money isn’t the driver,” says Mr. Pabrai, 42, who has three times bid hundreds of thousands of dollars in an annual charity auction to have lunch with Mr. Buffett. He was outbid each time. The India-born Mr. Pabrai has his own following among investors. His third book, “The Dhandho Investor,” is currently on Amazon.com’s bestseller list. He applied to work for Mr. Buffett in 1999 before he started his own fund, offering to sweep floors and to forgo pay. Mr. Buffett declined the offer. “If Jesus asked me to do something, there would be no discussion of compensation,” Mr. Pabrai says.

Mr. Buffett doesn’t plan on using slave labour, and in fact, the CIO job has the potential of very high compensation. He plans to pay the manager a certain percentage, say, ten percent, of his or her outperformance of the S&P 500 over a five-year rolling average.