American Express (AXP) met third-quarter earnings estimates late Wednesday, but failed to reverse a trend of ever-slower growth. Earnings per share rose 6% to $1.09, in line with analyst estimates, but down from double- and triple-digit gains in prior quarters, and the smallest rise in three years. CEO Kenneth Chenault acknowledged that spending by cardholders slowed from earlier this year and said the drop is part of "a trend among major card