What does the last sentence mean?
Buffett proudly announced that in a matter of months, BHA (Berkshire Hathaway Assurance) already has collected premium volume of $400 million, which may be more than all other municipal bond insurers—combined! It’s done 278 transactions, mostly secondaries, with just 30 people in the office. The Berkshire-insured bonds are trading at a premium to those of any other bond insurer.
Buffett said that the premiums represent coverage that only pays if the primary insurer cannot pay. And Berkshire is getting better than 2% when the original insurance cost 1%.