Warren's shares take Buffetting

Shares in Warren Buffett's Berkshire Hathaway have fallen almost 20% so far this year. The Standard & Poor's 500 index fell 15% in the same period.

The stock's worst performance for almost 20 years has been blamed on increasing price competition in the insurance market. One of Buffett's favourite sectors, it accounts for about a half of Berkshire's revenue.

Buffett warned investors of the encroaching gloom in his letter to shareholders in February. After reporting record 2007 earnings of $13.2 billion (£6.6 billion), he said profit margins from insurance would drop.

"That party is over," he added. "It is a certainty that insurance-industry profit margins, including ours, will fall significantly in 2008."

Berkshire has also has been hurt by the declines of bank and finance investments Wells Fargo, American Express and US Bancorp.

Despite the falls, Berkshire shares are still trading at $120,000 each.