Four banks were charged with fraud on Wednesday for their roles in a €1.7bn ($2.3bn) financing package for the Italian city of Milan in a case that will fuel the global debate about the use of complex derivatives. UBS, JPMorgan Chase, Deutsche Bank and Germany’s Depfa will face trial in Milan after a judge ruled there was sufficient evidence for them to face criminal charges of aggravated fraud for their role in devising a swaps package for the city’s 2005 bond issue.