Warren Buffett's company recently discovered it owns two short-line railroads it must sell because of its 2010 acquisition of the Burlington Northern Santa Fe railroad.
Berkshire Hathaway said in a letter to the Surface Transportation Board that the BNSF deal should have subject to the board's scrutiny because two of its subsidiaries own the small railroads.
By the end of the year Berkshire says it will sell the CBEC railroad that serves its MidAmerican Energy coal plants near Council Bluffs, Iowa, and the White City Terminal Union railway that serves an Oregon industrial park.
Before the BNSF acquisition, Berkshire sold its 9.6 million shares of Union Pacific Corp. and 1.9 million shares of Norfolk Southern Corp. to avoid problems with regulators.
Buffett's company didn't immediately respond to a message Tuesday.