WHAT goes around comes around. Sometimes it happens sooner than you'd think.

That round wheel turned on JPMorgan Chase last week, which disclosed that it had suffered a $2 billion trading loss in credit derivatives. That such a hit had befallen the mightiest of banks was perhaps more stunning than the size of the loss.

So where does the karma come in? The loss, and the embarrassment it held for Jamie Dimon, the bank's imperious chief executive, came just one month after a private dinner party in Dallas at which he assailed two respected public figures who have pushed for policies that would make banks like JPMorgan smaller and less risky.

One was Paul Volcker, the former Federal Reserve chairman, whose remedy for risky trading by too-big-to-fail banks is known as the Volcker Rule. The other was Richard W. Fisher, president of the Federal Reserve Bank of Dallas, who has also argued that large institutions should be slimmed down or limited in their risky trading practices.

The party, sponsored by JPMorgan for a group of its wealthy private clients, took place at the sumptuous Mansion on Turtle Creek hotel. Mr. Dimon was on hand to thank the guests for their patronage and their trust.

During the party, Mr. Dimon took questions from the crowd, according to an attendee who spoke on condition of anonymity for fear of alienating the bank. One guest asked about the problem of too-big-to-fail banks and the arguments made by Mr. Volcker and Mr. Fisher.

Mr. Dimon responded that he had just two words to describe them: "infantile" and "nonfactual." He went on to lambaste Mr. Fisher further, according to the attendee. Some in the room were taken aback by the comments.