Deutsche Boerse, London Stock Exchange, Nasdaq and Nyse Euronext have lined up as possible buyers of the state-controlled Warsaw Bourse.
The four competitors made preliminary offers for the exchange, which is 99% state owned, last month and have now been given the go-ahead to examine its finances.
Nasdaq controls exchanges in Lithuania, Latvia and Estonia. It is the only bidder that owns stakes in bourses in Eastern Europe.
The Warsaw bourse's sale is part of Poland's plan to raise 12 billion zloty ($3.9 billion) from the disposal of state assets this year. It plans to sell between 51% and 73.8% in the first stage of the privatisation and another 25% in two to three years.
The Warsaw Exchange is battling Wiener Börse for dominance in Central and Eastern Europe. Last year it acquired a 25% of Ukraine's Innex Exchange but lost out to Vienna in bids to take controlling stakes in the Prague and Slovenian bourses.