Mr Buffett has not been helped by the global recession
Celebrated US financier Warren Buffett has seen his investment firm report its first loss in eight years due to a badly-timed purchase of oil stocks.
Berkshire Hathaway made a loss of $1.53bn (£1bn) in the first three months of 2009, compared with a profit of $940m a year earlier.
The firm said it had to write down $1.9bn to reflect the reduced value of its stake in oil firm ConocoPhillips.
It bought the shares before oil prices fell sharply towards the end of 2008.
Mr Buffett had already admitted in February that the ConocoPhillips deal represented "terrible timing".
Berkshire Hathaway also made a first quarter loss of $986m in the derivatives markets, including bond trading.
Revenues were down 9.5% from a year before to $22.8bn.
Dubbed the "Sage of Omaha", billionaire Mr Buffett is widely celebrated for his investment acumen.
However, back in March he admitted that he had made some "dumb" mistakes during 2008.
The errors came as the bubble burst in the global economy last summer, causing global commodity prices to fall sharply as the world entered recession.
Berkshire Hathaway's other major investments include stakes in drinks giant Coca-Cola and bank Wells Fargo.