Discover Financial Services DFS, -6.79% unseated American Express Co. AXP, -5.09% as the credit card with the highest U.S. consumer satisfaction rating, according to J.D. Power's 2015 U.S. Credit Card Satisfaction Study. Discover card nabbed its highest ever score with 828-out-of-1,000 possible points. The survey grabbed data from more than 20,000 credit card users and looked at credit card terms, billing and payment, rewards, benefits and services, problem resolution and channel activities--Discover ranked the highest in every category, J.D. Power said. This marks the first time since the survey began in 2007 that Amex hasn't been No. 1. Discover's new security feature which allows customers to freeze a credit card via the company's mobile app helped give Discover the edge, said J.D. Power's Senior Director of banking services Jim Miller. Discover's rewards program was also a factor he said. Discover shares have slumped 15% in the year to date, while the S&P is up 1%.