Bank Zachodni WBK S.A. (Bank Zachodni WBK, BZ WBK) was established following the merger of Bank Zachodni with Wielkopolski Bank Kredytowy. The new Wroclaw-based entity was entered into the business register in the National Court Registry on 13 June 2001 and on 23 June 2001 it debuted on the Warsaw Stock Exchange. Both predecessors of Bank Zachodni WBK were spun off the National Bank of Poland in 1989. Subsequently, they were privatised and became members of the AIB Group under control of the same investor, i.e. AIB European Investments Ltd. from Dublin, which is a subsidiary of the Allied Irish Banks, p.l.c. (AIB). After the merger, the AIB Group became owner of a 70.5% stake in Bank Zachodni WBK. The shareholding declined to 70.4% following an increase in the share capital on 10 July 2009.

Bank Zachodni WBK S.A. („BZ WBK”) received the notification from Banco Santander S.A. on 1 April 2011 on the number of shares purchased through the bid for BZ WBK shares announced on 7 February 2011, and the percentage share in the total number of votes gained through the bid, i.e. on exceeding 90% of the total number of shares in the share capital and votes at the general meeting of shareholders of BZ WBK.