American Express Company (AXP) stocks fell 2.7% yesterday, following Bank of America Securities analysts downgrading the integrated payments company to Neutral from Buy. Analysts raised concerns as the stock is operating in a challenging spending environment and has a premium valuation, which is limiting its upside potential.AXP Stock’s ValuationAmerican Express' valuation seems expensive at the current levels. The stock is now trading at 17.31X forward 12-month price-to-earnings, which is higher than its f ...