Investment banks financing the purchase of US data storage group SunGard, the largest leveraged buy-out since the 1980s, are struggling to find buyers for the debt, raising fears that the downturn in high-yield markets threatens a new class of large private equity deals.

Deutsche Bank, JPMorgan and Citigroup recently began syndicating a $4bn (£2.09bn) bank loan, part of the financing of the $11.3bn deal, to hedge funds and other preferred investors before moving on to a formal roadshow.