American Express shares are trading lower in after-hours activity following the news that the US Office of the Comptroller of the Currency ordered American Express National Bank to pay a $350 million civil penalty. The regulator cited deficiencies in the bank's anti-money laundering program, a significant development that appears to be weighing on investor sentiment despite the company's recent focus on growth initiatives like its airport lounge expansion and AI-driven business tools. This negative catalyst follows a regular session where the stock had posted modest gains, contrasting with the broader financial sector which saw positive performance from peers like Synchrony Financial and Visa.