Warren Buffett's $48 Billion American Express Stake Has Been a Huge Winner. The Latest Results Say the Streak Is Far From Over.

AXP raised full-year profit guidance after third-quarter results showed 9% revenue growth, 3.1 million new card members, and a 38% return on equity. The guidance hike is the headline catalyst for a stock that has delivered 440% total returns over the past decade.

The company is also investing in AI partnerships with OpenAI to drive future growth, according to the source. No financial impact from that effort has been quantified.

The results carry weight beyond AXP itself. American Express is Berkshire Hathaway's second-largest holding, valued at $48 billion. That makes the quarter relevant to BRK.A and BRK.B holders, since a position of that size ties the performance of Warren Buffett's conglomerate to AXP's earnings trajectory.

Interpretation: a 38% return on equity paired with 9% top-line growth suggests the company is generating strong profitability on its capital base, while 3.1 million new card members point to continued customer acquisition. The decision to lift guidance rather than reaffirm it signals management confidence in the remainder of the year. The 440% decade-long run also means expectations are elevated, so the bar for future quarters is high.