Warren Buffett is an iconic figure in the finance realm. Buffett’s holding company, Berkshire Hathaway (BRK.B), has focused its investment strategy on identifying undervalued companies and holding them for the long term. This strategy has become a model for aspiring investors. One such stock that has earned a place in Buffett’s equity portfolio is American Express Company (AXP), also known as AmEx. The company has been a long-standing player in the global financial industry. American Express accounts for 8.8% of Berkshire’s holdings – just behind Apple (AAPL) and Bank of America (BAC), and ahe…