Euronext has confirmed that it has submitted a non-binding offer to the London Stock Exchange Group to buy Borsa Italiana,.
Sources also said today that Swiss operator Six had submitted its offer.
Euronext's partners in the offer include Italy's Cassa Depositi e Prestiti (CDP) Equity and Intesa Sanpaolo, it said in a statement, adding there was no certainty that the offer would lead to a transaction.
Euronext operates stock exchanges in Dublin, Paris, Amsterdam, Brussels, London and Lisbon.
The London Stock Exchange (LSE), which bought Borsa Italiana in 2007 for €1.6 billion, is now trying to sell it as part of competition remedies for its $27 billion takeover of financial data provider Refinitiv.
The move has put Borsa Italiana, which runs the Milan stock exchange, at the centre of a potential shake-up in the European exchange sector, which has long been under pressure to consolidate further.
"This transformational project would effectively position the newly formed group to deliver the ambition of further building the backbone of the Capital Markets Union in Europe, while at the same time supporting local economies," Euronext said today.
As expected, Six also submitted a non-binding offer for the Italian bourse, two sources familiar with the matter said today. The Swiss exchange operator declined to comment.
Euronext and CDP confirmed on Friday they were in talks to make a joint bid for the Italian exchange, as Germany's Deutsche Boerse submitted a rival offer.