(Reuters) -Discover Financial Services ( DFS ) on Wednesday reported a 70% rise in second-quarter profit, as a high-rate environment helped the U.S. credit issuer earn more in interest income.

The company's shares rose 4.7% to $148 in after-hours trading.

Credit card-focused lenders have outperformed the broader industry this year, benefiting from gains in interest income. Companies like Discover get shielded from market volatility in mortgages as customers do pay higher amount of interest amount on their credit cards.

Riverwoods, Illinois-based Discover recorded net interest income of $3.52 billion in the second quarter, nearly 11% higher than the same quarter last year.

Discover's provision for credit losses fell to $739 million in the quarter ended June 30 from about $1.31 billion in the year-ago period.

Discover's net income jumped to $1.52 billion, or $6.06 per share, from $895 million, or $3.54 per share.

Earlier in the day, Discover said it will sell a portfolio of student loans to buyout giants Carlyle and KKR for up to $10.8 billion.

Separately, Capital One said on Wednesday it would commit $265 billion over five years to lending, philanthropy and investment if its takeover of Discover goes through.

Its $35 billion Discover deal will create the biggest U.S. credit card issuer by balances and the sixth-largest bank by assets. It will also give Capital One control of Discover's card payment network, the fourth major payment network operator after Visa, Mastercard and American Express.