Jamie Dimon, chief executive of JPMorgan Chase, said he expected a "disruption" in the US bond market, prompting the Federal Reserve to intervene. "There's going to be some disruption in the Treasury market because of all the rules and regulations," Mr. Dimon said on Friday's earnings call, adding that the Fed would act then, but not until "they start to panic a little bit". Yields, particularly on long-dated bonds, rose sharply this week as Mr. Trump's tariff TV series triggered broader market turmoil. The move raised questions about whether the asset had lost its safe-haven appeal and raised concerns about a large unwinding of the basis trade.