Saturday's announcement that Berkshire Hathaway Inc. has chosen a likely successor to Chief Executive Warren Buffett will only add to the mystery over just who might fill the billionaire investor's shoes some day.

Mr. Buffett didn't name the candidate in his annual letter to Berkshire Hathaway shareholders, and offered little in the way of description other than to say the person is 'an individual to whom [directors] have had a great deal of exposure and whose managerial and human qualities they admire.'

Who might one day succeed Mr. Buffett has been a subject of speculation in the media and among investors for years. The brief descriptive comments in the letter suggest a workingrelationship between the board and the successor-designate.

The list of commonly mentioned candidates includes Mr. Buffett's insurance lieutenant, Ajit Jain; Matt Rose, the head of Berkshire's railroad operation; and Gregory Abel, chairman of the company's energy unit. Two lesser-known candidates, Tony Nicely, who runs Berkshire-owned Geico Corp., and Tad Montross, of Berkshire's General Re unit, sometimes make the roster as well.

The names are largely a compilation of guesses by shareholders and the media, based in part on the public praise that Mr. Buffett has showered on each of them in forums such as the annual letter and Berkshire's annual shareholder meeting. The guesswork arises because Mr. Buffett has been cagey on the subject of his potential successors.

Mr. Jain, who runs a reinsurer within Berkshire that takes on massive risks, built the operation from virtually nothing. At last year's annual shareholder's meeting, Mr. Buffett heaped praise on Mr. Jain for always thinking of Berkshire first, making Mr. Jain the presumptive front-runner in the wake of the departure of another executive, David Sokol, who had been seen as a top CEO aspirant.

Mr. Jain, Mr. Buffett has said, long ago could have departed Berkshire for a higher-paying job. 'People would hand him a significantpercentage of any company with lots of money.