He compared money managers who promise double-digit returns to the queen in “Alice in Wonderland,” who proclaimed, “Why, sometimes I’ve believed as many as six impossible things before breakfast.” Mr. Buffett added, “Beware the glib helper who fills your head with fantasies while he fills his pockets with fees.”

Mr. Buffett pointed out that some companies with pension plans in both Europe and the United States assume better returns on the American plans than the European ones.

“This discrepancy is puzzling,” he said. “Why should these companies not put their U.S. managers in charge of the non-U.S. pension assets and let them work their magic on these assets as well? I’ve never seen this puzzle explained. But the auditors and actuaries who are charged with vetting the return assumptions seem to have no problem with it.”

“What is no puzzle, however, is why C.E.O.s opt for a high investment assumption: It lets them report higher earnings. And if they are wrong, as I believe they are, the chickens won’t come home to roost until long after they retire.”

Mr. Buffett also had harsh words for state and local governments. “Public pension promises are huge and, in many cases, funding is woefully inadequate. Because the fuse on this time bomb is long, politicians flinch from inflicting tax pain, given that problems will only become apparent long after these officials have departed. Promises involving very early retirement  sometimes to those in their low 40s  and generous cost-of-living adjustments are easy for these officials to make. In a world where people are living longer and inflation is certain, those promises will be anything but easy to keep.”

He did not discuss why he wanted to insure municipal bonds issued by governments making such promises.

Mr. Buffett also warned of lower profits ahead for the insurance industry, which has benefited from two years without major disasters.