How the Crunch Is Playing Out

In recent weeks, every major bond insurer has reached out to Berkshire -- owner of a range of companies including reinsurer General Re Corp. and auto insurer Geico -- as a source of capital relief while their financial strength comes under scrutiny by ratings firms and investors, according to these people. In the process of pleading their cases with Berkshire, these companies provide Mr. Buffett with opportunities to size up their businesses.