UniCredit SpA , Italy ’s No . 1 bank , said hackers took biographical and loan data from 400,000 client accounts in one of the biggest breaches of European banking security this year . The attack occurred in September and October of 2016 and June and July of this year , according to an emailed statement from the bank on Wednesday . UniCredit only discovered the breaches this week , two people familiar with the matter said , asking not to be identified discussing a possible criminal matter . ;