Greece may struggle to form a bad bank under a financial-industry restructuring because of the complexity of local soured debts and a shortage of cash, according to Fitch Ratings Ltd.

The nation’s non-performing loans are mostly from the commercial sector, so they are varied and difficult to manage, according to Erwin van Lumich, Fitch’s managing director for financial institutions. That contrasts with Spain, where a bad bank set up in 2012 mainly took on soured real-estate debt, with much less diverse terms.

“It’s potentially easier to manage those assets because it’s a pool of relatively homogeneous loans,” Lumich said by phone. “Whereas in Greece, a bad bank would likely be dealing with a more diverse range of loans.”

Forming a bad bank may be key to recapitalizing Greek lenders, which have amassed at least 30 billion euros ($33 billion) of non-performing loans because of the nation’s economic collapse. Prime Minister Alexis Tsipras also made last-minute concessions on Thursday in a bid to win a 53.5 billion euro bailout from creditors.

The country will probably need overseas aid or private investment to set up a bad bank, Lumich said.

“It’s difficult to see how the sovereign could fund a bad bank without external support,” he said.