Earnings at American Express ( AXP) rose 17% in the third quarter on the strength of higher spending by the firm's charge-card customers. In the quarter, the financial services firm earned $1 billion, or 82 cents a share, up from $879 million, or 69 cents a share, a year ago. Revenue rose 11% to $6.1 billion. But expenses rose 12% in the quarter to $4.5 billion, as American Express spent 16% more on marketing and promotions. The third-quarter results include earnings from the firm's former financial planning arm, Ameriprise Financial ( AMP), which was spun off on Oct. 3. The firm attributed much of the gains in revenue to an 18% surge in spending by its card members. The higher spending generated a 16% gain in so-called "discount revenue" to $2.94 billion. Income from securitizations rose 20% to $353 million. Finance charges on loans to card members rose 15% to $648 million. In the quarter, American Express' provision for losses rose 33% to $739 million. The company said much of that increase stemmed from losses related to the aftermath of Hurricane Katrina. "This quarter's performance underscores the strength and momentum of an American Express that is now focused on the global payments business,'' said the company's CEO, Kenneth Chenault. Shares of American Express were most recently trading at $48.70, up $1.55, or 3.3%.