Fitch Lowers Outlook on Berkshire Hathaway

Concern about an insurance investigation and the ability to find a successor who could match billionaire Warren E. Buffett’s investment expertise led Fitch Ratings to lower its outlook Tuesday on Berkshire Hathaway Inc.’s triple-A bond rating from stable to negative.

Buffett, 74, is in good health and shows no signs of retiring, but his inevitable departure as chairman and chief executive of Berkshire would make it difficult for the company to sustain its current strategies, Fitch said in a news release.

Among other things, Buffett’s reputation lets him accumulate Berkshire’s cash and concentrate its investments in a way that would not be accepted at most other public companies, Fitch said.

Buffett was traveling Tuesday and could not immediately be reached for comment.

Berkshire insurance subsidiary General Reinsurance Corp. has been a subject of a federal investigation into reinsurance transactions with American International Group Inc. Buffett is not a target of the investigation but was interviewed by regulators.

Berkshire’s stock closed down $220.10 on Tuesday to $85,089.90 on the New York Stock Exchange.