The accord values BPER's loan recovery business, which comprises staff dedicated to recouping problem loans and the technology they use, at 150 million euros.
Gardant, controlled by U.S. fund Elliott, will acquire 70% of the unit, with BPER retaining 30%.
Reuters in May was first to report that Gardant had teamed up with AMCO in the hard fought deal for BPER's division.
BPER was the only major Italian bank to still have full control of its debt recovery operations and the Gardant-AMCO duo trumped rival bids by Sweden's Intrum, Davidson Kempner-owned Prelios and Softbank-backed doValue.
Gardant had struck a similar deal with Banco BPM four years ago.
Banks normally offloads the recovery units at a profit which they use to offset the hit from simultaneous bad loan disposals.
BPER is shedding up to 2.5 billion euros in bad debts as part of the Gardant-AMCO deal.
By the end of the year, BPER will sell a first 1.5 billion euro bad loan portfolio to AMCO, which is able to bid higher than privately-owned rivals in tenders thanks to lower funding costs.
Under a 10-year management accord, the new Gardant-controlled joint venture will handle part of BPER's existing bad loans, including some of those which it is selling.
It will also get 90% of all new defaulted loans and 50% of new 'unlikely-to-pay' loans - which are not yet in default.
($1 = 0.9538 euros)
(Reporting by Valentina Za and Andrea Mandala; Editing by Agnieszka Flak)
