American Express posted a big beat on first-quarter earnings and revenues after Wednesday's closing bell.

The financial-services giant earned $1.45 in adjusted earnings per share (EPS), on revenues of $8.1 billion. Analysts had expected EPS of $1.33 and revenues of $8.05 billion, according to Bloomberg.

"Despite strong competition throughout the payments industry, we generated a 4 percent increase in FX-adjusted revenues," CEO Ken Chenault said in the earnings release.

The company's revenues were also boosted by increased card-member spending. At the same time, aggressive marketing and reward offerings increased total expenses by 2% to $2 billion.

The company reaffirmed its forecast for full-year earnings.

Its shares had fallen about 15% over the last year through Wednesday's close. They rose by as much as 3% in after-hours trading.

Last year, American Express lost two key co-branding partnerships, with Costco and JetBlue. It announced the sale of the Costco portfolio to Citi in February.