Thanks to strong business operations, Discover Financial Services (NYSE:DFS) announced that its earnings per share jumped from $1.20 in the second quarter of 2013 to $1.35 in the most recent quarter.

Net income available to Discover shareholders rose 7% to stand at $630 million for the three months ending in June. With the number of common shares falling by 5% thanks to repurchases, earnings per share rose by 13%.

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Income growth came down almost entirely to the loan portfolio, which rose by $4.2 billion over the past year to stand at $65.9 billion. Credit card loans rose by $3 billion, or 6%, over the past year. Discover also saw sizable expansion in its personal loans, which grew 26% to $4.6 billion.

Net interest margin -- the difference between what a company collects on loans versus what it pays out on deposits and other borrowings -- expanded from 9.44% in the second quarter of last year to 9.84% in the most recent quarter.

As a result of the growth in its loan portfolio plus the expansion of rates, Discover's net interest income rose 11% to $1.6 billion.

Discover did see a $10 million decrease in its Protection Products Revenue, and other income fell by $40 million as a result of lower mortgage-related income.

However, this drop was almost entirely offset by a $37 million drop in other expenses. Somewhat surprisingly, the company also saw its marketing and business development expenses fall by 9%, or $17 million.

"Our record earnings per share this quarter reflect outstanding fundamental performance in our Direct Banking segment in terms of loan growth and credit performance," said Chairman and CEO David Nelms in the earnings announcement. "Our continued focus on gaining wallet share with existing customers and acquiring new accounts with Discover IT drove strong card receivables and sales growth of 6%."

Overall, the operating businesses at Discover has been on an impressive run as of late, and this quarter was no exception.

Patrick Morris and The Motley Fool own shares of Discover Financial Services. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.