Although they remain significantly higher than the rates at credit unions, delinquency rates at big bank card issuers are still falling, according to industry analysts at SNL Financial.

The lowest rate remained at American Express, which saw its delinquency rate remain at 1.31% while Discover's delinquency rate slid from 1.93% to 1.88%. 

Big bank issuer Bank of America saw its rate move from 3.32% to 3.23%, while JP Morgan Chase's rate slipped from 2.09% to 2.06% and Citigroup's moved down to 2.44% from 2.55%.

Charge off rates at the largest issuers also fell, the firm reported. 

Analysts attributed the drop to continuing improvement in credit card credit quality.

By comparison, at the end of last year card delinquency at credit unions nationwide averaged 1.15%, according to the credit union consultancy Callahan and Associates.