Berkshire Hathaway fourth-quarter profit up on derivatives

Berkshire Hathaway CEO Warren Buffett attends the Allen & Co Media Conference in Sun Valley, Idaho July 12, 2012.

REUTERS - Warren Buffett's conglomerate Berkshire Hathaway (BRKa.N) reported a larger fourth-quarter profit on Friday, boosted by derivative gains.

The company posted a profit of $4.56 billion, or $2,757 per Class A share, compared with a profit of $3.05 billion or $1,846 per Class A share a year earlier.

Year-end book value, Buffett's preferred measure of the stock's worth, rose 14 percent to $114,214 per share.

Earnings were boosted by $1.4 billion in derivative gains during the quarter. Otherwise, operating earnings rose only slightly in the period.

Berkshire shares have been on a tear of late, gaining more than 13 percent this year. Both the Class A and Class B stock touched all-time highs Thursday.

(Reporting by Ben Berkowitz; Editing by Bernard Orr)