NEW YORK ( TheStreet) -- American Express ( AXP)'s selloff Wednesday offers investors a chance to take another look at a solid long-term investment that may not get a whole lot cheaper. American Express had been gaining some momentum in recent days, as a disappointing July 18 second quarter earnings report slowly faded into the rear view mirror. Shares lost nearly 5% from the day of the report through Friday, Aug. 10, while the S&P 500 rose 3.08% and Capital One Financial ( COF), Visa ( V), and Discover Financial Services ( DFS) all posted gains. Mastercard ( MA), meanwhile, lost a more modest 2.20% during the same time frame. From Aug. 13 through Tuesday, on the other hand, Amex shares gained almost 5%, while the S&P and those same peers were essentially flat. The one exception was Discover, which got a big boost from its announcement of a mobile payments deal with eBay ( EBAY)'s PayPal. Wednesday, however, American Express shares lost 2.41%, worst in the group. Analysts were divided over the reason for Wednesday's loss, with Jamie Friedman of Susquehanna Financial Group attributing the drop to weak August volumes from merchant acquirer First Data and David Darst of Guggenheim Securities arguing investors dumped shares of Amex (as well as Discover, which also fell more than 2%) to buy into a discounted secondary share offering from Capital One. Neither Darst, who cut Amex to neutral July 19, nor Friedman, who has a buy on the name, are especially optimistic about spending trends shown by Amex customers. Friedman's buy rating is based mostly on a belief that Amex will show progress on cost cutting initiatives. Credit card sector analysts aren't economists, however, and there's plenty of evidence the economy is slowly getting into gear. If it isn't, Amex knows how to play defense. If it is, the cautious tone of analysts like Friedman and Darst suggests the upside may be juicier than one would ordinarily expect from an industry leader like Amex. -- Written by Dan Freed in New York. Follow this writer on Twitter.