Updated 10:40 a.m. ET The polite term is that stocks are mixed Friday. It means this for now: The Dow Jones Industrial Average is higher, thanks in part to gains for American Express, pushing toward a 4% gain, because its core customers  — the affluent  — are doing what they do: They're continuing to spend. The company's earnings of $4.14 a share on record revenue of$18.4 billion beat Wall Street estimates for earnings of around $4 on revenue of$18 billion. So, too, is Visa because customers are usin ...