The average credit card net loss rate for the six major U.S. credit card issuers dropped below 1% for the first time in at least a decade in September.

The group average for the credit card annualized net loss rates for six major credit card issuers — JPMorgan Chase & Co., American Express Co., Citigroup Inc., Bank of America Corp., Capital One Financial Corp. and Discover Financial Services — fell to 0.93% in September, compared to 1.15% in August and 1.96% a year ago, according to data collected by S&P Global Market Intelligence. It was the lowest loss rate and the first time being under 1% since Market Intelligence started tracking master trust data more than a decade ago.

"Net charge-offs are the lowest we've experienced in recent history," said JPMorgan CFO Jeremy Barnum during the bank's third-quarter earnings call, talking about overall credit trends at the bank. Barnum pointed to the card business as a main driver for the favorable metrics.

With delinquencies remaining very low, JPMorgan lowered its outlook for card net charge-offs to about 2%.

The strong credit quality metrics came as banks pointed to cards as a source of loan growth.

"Card balances are growing. ... As people get back to work in higher wages and things, there's just more money to spend," said Bank of America CEO Brian Moynihan during the bank's third-quarter earnings call.

Delinquency rates for major U.S. card issuers were down on a year-over-year basis to 0.79% in September, compared to 1.14% a year ago. However, the delinquency rate was a bit higher than the 0.76% reported in August.

Bank of America executives expect another decline in card losses in the fourth quarter, given the continued low level of late-stage delinquencies, before it levels off.

American Express posted the highest year-on-year increase in gross master trust portfolio yield in September, followed by JPMorgan and Capital One. All three saw a year-over-year increase of more than 150 basis points.

While Citigroup posted the smallest year-on-year increase in card portfolio yield among its peers with a 7-bps bump, the bank posted the largest year-over-year declines in annualized net loss rate and delinquencies in September.

Citigroup CFO Mark Mason said during Citigroup's third-quarter earnings call that the bank is encouraged by the trends it sees in cards, citing a 24% year-over-year increase in purchase sales for its branded cards.

Mason said Citigroup is seeing growth in its on-card lending products such as Flex Pay and Flex Loan, which he said have generated interest from announcement.