The second largest buyout in the financial sector has come under threat as alternative investment firm JC Flowers warned it may not be able to complete the $25.5bn (€18.6bn) acquisition of Sallie Mae, the US student loan provider.

JC Flowers, private equity firm Friedman Fleischer & Lowe, Bank of America and JP Morgan Chase agreed to acquire the lender in April. However, Sallie Mae said yesterday it had been informed by the consortium that legislative proposals pending before the US House of Representatives and Senate could prevent the deal closing.