American Express generates roughly $12 billion in annual card interest revenue, representing nearly one-third of the company’s total net revenues. A 10% cap on APRs would force AXP to write down interest margins by an estimated $3–4 billion per year, based on average balances of over $180 billion in U.S. card receivables. Such a reduction could shave as much as 15% off the company’s operating profit if enacted.

Jefferies credit-card analyst Darren Jerolmack recently published a report stating that legislative hurdles and industry lobbying make a permanent 10% cap “highly unlikely.” He notes that similar proposals in previous election cycles have stalled in committee and that AXP’s Washington relations team has long maintained close ties with key Senate Banking Committee members. Jerolmack assigns just a 25% chance of any cap proposal becoming law this year.

While the immediate legislative threat appears limited, investors should monitor three key metrics: U.S. cardholder loans, which grew 18% year-over-year to $175 billion in Q4; net interest margin, which expanded to 11.8% in the last fiscal quarter; and lobbying expenditures, where AXP boosted spending by 20% in the past 12 months. Any sudden shift in these figures could signal renewed regulatory pressure or success of cap proponents, prompting multiple contraction in AmEx shares.