In the fourth quarter, Guy Spier’s Aquamarine Capital executed a significant reduction in its position in American Express, trimming the stake by approximately 69%. This move made American Express one of the largest sell orders in the fund’s portfolio for the period. The sale lowered the company’s weight in Aquamarine from roughly 8% of the total fund value to just under 3%, reflecting Spier’s view that the stock’s near 24 times trailing price-to-earnings multiple is demanding for a business tied closely to middle-income consumer spending.

President Donald Trump has called on Congress to impose a temporary cap of 10% on credit-card interest rates for one year, a policy that directly threatens the revenue model of issuers like American Express. With average card APRs currently hovering between 17% and 23%, a cap at 10% could slice interest income by up to 50%, according to industry estimates. The credit-card issuer has not publicly adjusted its pricing but must now prepare for possible legislative action before the January 20 deadline.

JPMorgan Chase CEO Jamie Dimon warned that a stringent interest-rate ceiling would constitute an 'economic disaster,' forecasting a contraction of credit-card lending for 80% of U.S. consumers. For American Express, which generates nearly 60% of its profits from interest and fees, such a cap could force the elimination of up to 20% of its receivables base, based on consensus estimates. Investors will be watching the next quarterly report for signs of margin compression and any changes to the company’s consumer-lending strategy.