Investors awaiting Warren Buffett’s annual letter will get three for the price of one this year. The founder of Berkshire Hathaway is planning a special golden anniversary publication, marking 50 years since he took a controlling stake in the company.

Adam Jeffery | CNBC

Warren Buffett

By writing about the next 50 years, the two men, who have a combined age of 175, will be attempting to shape the future of Berkshire — and their legacy — amid an intensifying debate about what this unusual company will look like when they are gone.

They took an ailing New England textile business and turned it into one of the most successful investment vehicles in history, through a combination of acquisitions in insurance and other industries and a portfolio of equity investments in American icons such as Coca-Cola. McDonald’s and American Express. Over the past generation, as shareholders at other companies have demanded a focus on a core business, Berkshire has only diversified more.

Now, with the addition of US power companies, one of North America’s largest railways and a 50 per cent stake in Heinz, it is probably the world’s most diverse conglomerate; it is certainly the largest. With a market value of $358bn, it is bigger than General Electric.

As Mr Buffett, 84, the company’s chairman, chief executive and chief investment officer, has aged, the debate about whether the ragbag entity should be split apart after his retirement has only got louder. But the debate may be shifting. While he and Mr Munger, the 91-year-old vice-chairman, insist that they have built an enduring company with a culture all its own, investors, analysts and long-time Berkshire watchers are focusing on more nuanced questions of management structure.

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The most important thing to Warren Buffett is, how can he position Berkshire for the future so that it continues to generate increased value for shareholders, says Jay Gelb, an analyst who covers the company for Barclays and who is invited each year to pose questions to Mr Buffett at Berkshire’s annual meeting. I think this could be his most important annual letter yet.

Mr Buffett’s missives, which come out around the end of February and run to 30 pages or so, are packed with nuggets of investment wisdom, expansive pedagogical passages and jokes. The world’s most successful fund managers, private equity bosses and corporate chief executives cite them as influences and read them just as voraciously as any small shareholder or business student.

Yet perhaps the letters’ biggest role is to be the glue that holds Berkshire together, the philosophical foundation of a confounding company.

The forthcoming Buffett and Munger road maps for the next 50 years could act as companion to the Owner’s Manual Mr Buffett wrote for Berkshire shareholders in 1996, in which he set out 15 guiding principles. These included a promise to seek solid businesses and to hold them forever, instead of chasing quarterly earnings and churning the portfolio. It also enshrined Berkshire’s management culture, which leaves subsidiary company bosses to run their own show, without interference from the head office in Omaha, which is still staffed by just 25 people.

The annual letters include pointed exhortations against paying dividends or taking on too much debt, all of which will be hard for Mr Buffett’s successors to ignore, and which they can use in answer to outsiders urging change.