Italian bourse CEO says there are 'colossal' short positions on Italy

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Big international investors are holding huge short positions on Italian assets, the CEO of the Italian exchange said on Tuesday, days before the country holds a referendum on constitutional reform that could unseat Prime Minister Matteo Renzi.

"There are colossal short positions on Italy from the U.S. and other countries where big investors are based," said Raffaele Jerusalmi during a conference in Milan.

Opinion polls conducted until a blackout period began last week showed the "no" vote comfortably in the lead, raising concerns of a political crisis and fueling market volatility.

Renzi has said he would resign if Italians reject the reform.