American Express has enjoyed several years of accelerated growth as its new card acquisition and loan growth have significantly outpaced peers'. The company has historically been a payment network first and lender second. While this hasn’t changed—it still gets only about 25% of its revenue from net interest income—its shift toward a younger cardholder base and more lending features on its cards drove 26.1% compound annual growth in net interest income from 2021 to 2024, providing a major tailwind for overall growth. While this growth has decelerated, as specific strategic and product shifts ran their course, the firm’s shift toward younger cardholders should provide a long-term tailwind to NII. As a case in point, NII increased 12% in 2025, below the previous three-year average but still well above the industry average.