US private equity firms Carlyle and KKR are the top bidders to acquire a $10 billion US student loan portfolio from Discover Financial. Other firms, including Ares, Blackstone, Brookfield, Fortress, and Oaktree, have also submitted bids. Discover announced the sale of its student loans portfolio in November as part of a strategic review. The deal is expected to conclude later this month or early in July. [175005bc]