Discover's net charge-off rate during July for managed card balances was 2.22%, improving from 2.40% in June. American Express's net loss rate for cards declined to 1.95% in July, from 2.18% the previous month.

Capital One Financial ( COF) reported that the net loss rate for its managed card balances rose to 2.91% in July, from 2.72% in June. Citigroup ( C) unit Citibank's credit card master trust reported a July charge-off rate of 4.28%, increasing from 3.74%, while JPMorgan Chase ( JPM) unit Chase Issuance Trust saw net charge-offs increase to 4.58% in July, from 3.71% in June.

Bringing up the rear was Bank of America ( BAC), with its credit card trust reporting a July loss rate of 5.05%, increasing only slightly from 5.04% in June.

Since July card trust data wasn't yet available for all of the large card lenders, Hagerman compared the July 31 master trust card portfolios to balances at the end of June 2011. Over that 13-month period, all six of the card lenders in the report saw total managed credit card receivables in master trusts decline. Bank of America showed the largest decline of 15%, to $61.1 billion, while Discover showed the 13-month smallest decline, of 1.5%, to $32.8 billion.

Discover's shares have now returned a stellar 61% year-to-date, following a 31% return during 2011. That is a remarkable run by any standard, especially when you consider that the S&P 500 Index ( SPX.X) was flat for 2011, while the KBW Bank Index ( I:BKX) declined 25%.

The shares trade for 2.4 times tangible book value, according to Thomson Reuters Bank Insight, and for 9.6 times the consensus fiscal 2013 earnings estimate of $3.99, among analysts polled by Thomson Reuters. The consensus EPS estimate for fiscal 2012 is $4.20. Discover's fiscal year ends on Nov. 30.

While Discover's price-to-tangible-book ratio may seem high in the current environment, with Citigroup and Bank of America trading for roughly 0.6 times tangible book value, while JPMorgan trades for 1.1 times tangible book, the company's very strong earnings track record justifies its valuation, and then some.

Discover's operating returns on average equity (ROE) have ranged between 24.21% and 33.42% over the past four quarters, according to Thomson Reuters Bank Insight. Bank of America -- saddled by its legacy mortgage mess springing from the disastrous purchase of Countrywide in 2008 - has seen its ROE over the past four quarters range from 1.12% to 11.21%. Citigroup's ROE has ranged from 2.18% to 8.41%.

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