JPMorgan Chase & Co. Chief Executive James Dimon sparred with lawmakers of both parties as an appearance in the U.S. House of Representatives proved more contentious than his Senate hearing last week, the Wall Street Journal reported today. Dimon faced pointed questions about the bank's lobbying on derivatives rules, risk models and on whether the bank is so large and complex that it would have to be rescued by the government if it were to fail. Several lawmakers accused Dimon of being more focused on trading activities than on lending to consumers. Rep. Maxine Waters (D-Calif.) pressed Dimon about the bank's opposition to a proposal that all trades made by U.S. banks, even those booked offshore, be included under new rules. Dimon said that proposal would harm the bank's ability to compete overseas. The bank's customers "will go elsewhere if we can't give them the best possible deal," he said. Earlier in the day, bank regulators said a lack of disclosure by JPMorgan regarding risks it was taking hampered efforts to prevent the trading losses of more than $2 billion the bank disclosed last month. Comptroller of the Currency Thomas Curry testified that the regulator is probing the level of reporting provided by JPMorgan's Chief Investment Office, the unit responsible for the losses.