US investment guru Warren Buffett is heading for his worst year relative to the rest of the US stock market since 2009, with shares in his conglomerate Berkshire Hathaway down 11.5 per cent with two more trading days to go.

The underperformance comes in Mr Buffett’s golden anniversary year at the helm, when he told investors for the first time that they should judge his record on Berkshire’s share price, rather than just the book value of the company - his preferred yardstick for decades.

Mr Buffett urged them to make that judgment based on the long term, rather than on a single year, reflecting investor Benjamin Graham’s view that the stock market may be a “weighing machine” in the long run, but in the short term it is a “voting machine”.

But in 2015, the market has voted negatively on Berkshire’s prospects for weathering the decline in commodities prices, according to Jim Shanahan, analyst at Edward Jones.

Shrinking oil industry

Although Berkshire has no oil and gas subsidiaries, its railway business transports oil, coal and agricultural products, and its manufacturing arm sells products to the shrinking oil industry.

“They are impacted by the weak resources sector and commodity prices in general,” said Mr Shanahan.

Berkshire has also been hit by big declines in two of its largest stock market investments: American Express, down 25 per cent this year, and IBM, down 13 per cent.

But net earnings rose 18 per cent to $18.6 billion (€17bn) in the first nine months of the year, and book value was up 3.3 per cent.

The fall in Berkshire shares comes against a 3 per cent return from the S&P 500, including dividends. It is only the 11th negative year since Mr Buffett took control in 1965, and the worst underperformance relative to the S&P 500 since 2009.

Copyright The Financial Times Limited 2015