Not long after Berkshire Hathaway uncharacteristically entered the takeover fray for Transatlantic Holdings, offering $3.25 billion, the credit ratings agency Standard & Poor’s had a surprise of its own: It lowered its outlook on Warren E. Buffett’s company.

While affirming the AA+ ratings of Berkshire Hathaway and four other insurers, S.&P. said it was revising its outlook on the five to “negative”

And in unrelated news:
Buffett says U.S. debt should be rated 'quadruple A'
Read more:

Obama's pal suffers a setback.