Abu Dhabi state-owned fund Aabar Investments is to sell its 3.3 percent stake in Italian motorway operator Atlantia for 321 million euros ($448 million) to an unnamed buyer, a preliminary bond prospectus showed.   

Aabar, majority-owned by Abu Dhabi's International Petroleum Investment Corporation (IPIC), bought the stake in Atlantia for 250 million euros from Italian bank UniCredit in December 2008.   

"Completion of the sale is expected shortly subject to closing conditions," the prospectus from IPIC said.

IPIC, which owns 86.2 percent of Aabar, picked six banks to undertake a fixed income roadshow in Asia, Europe, the United States and United Arab Emirates, a source told Reuters last week.

Aabar, the largest shareholder in German automaker Daimler, in June bought a 4.99 percent stake in UniCredit, which at that time was worth about $2.5 billion.

Aabar converted to a private joint stock company in August after delisting from the Abu Dhabi bourse. It reported a second-quarter loss of $376 million.

The bond prospectus also said IPIC's net profit for the six months to end-June fell 86 percent to $414 million.

IPIC said it incurred losses on derivative and non-derivative financial instruments totalling about $1.45 billion during the period, mainly relating to its investment in Daimler. - Reuters