How it started
Predecessors and 1997 merger
Bank Inicjatyw Gospodarczych (BIG SA) was established in 1989. Initially, 98% of shares in it were owned by Warta, Poczta Polska, PZU, Universal and Transakcja foreign trade headquarters (KC PZPR and ZSMP), and 2% were held by natural persons. In 1992 the Bank's shares debuted on the Warsaw Stock Exchange, the first public offering of a financial institution in Poland since the end of the Communist system.
Bank Gdański was one of nine banks spun off in the late 1980s from the National Bank of Poland, the culmination of a sequence of reforms during the 1980s that brought an end to the country's single-tier banking system. It was reorganized in 1991 as a joint-stock corporation.
In 1997 BIG merged with Bank Gdański to form BIG Bank Gdański, and Banco Comercial Português (BCP) acquired a 44.1-percent stake in the merged entity while Eureko acquired a further 15 percent.. A year later, in cooperation with BCP, BIG Bank Gdański launched the Millennium retail service network.
Later developments
By 2018, BCP held 50.1% shares of Bank Millennium.
From Wikipedia’s article on Bank Millennium, shared under CC BY-SA 4.0.2