(Adds details, background)
MILAN, June 4 (Reuters) - London-based private equity firm Pamplona Capital Management LLP has cut its stake in Italy's biggest bank by assets, UniCredit, to 1.9 percent from 4.9 percent, according to a filing posted on the website of market watchdog Consob.
The stake reduction took place on May 30, the filing showed on Wednesday.
The fund, backed by Russian billionaire Mikhail Fridman's Alfa Group, had increased its stake to 5.01 percent in UniCredit in June 2012 from 2 percent, becoming the bank's second largest shareholder at that time.
Deutsche Bank had provided financing to Pamplona for the stake increase, in a deal that involved also put and call options to be exercised by June 2014.
The price of UniCredit's shares has nearly trebled since June 2012 and stood at around 6.5 euros on Wednesday.
Following the transaction by Pamplona, U.S. investor BlackRock has become UniCredit's top shareholder with a 5.2 percent stake.
The second-largest shareholder in the bank is Abu Dhabi-based Aabar, with 5.08 percent stake, followed by Italian banking foundation Fondazione Cassa di Risparmio di Verona, Vicenza, Belluno ed Ancona. (Reporting by Gianluca Semeraro and Francesca Landini; Editing by Lisa Jucca)