Chi-X Europe says it has received an "enquiry" from an unnamed party that may lead to an offer for the multilateral trading facility (MTF).
In a statement, Chi-X Europe confirms that its board is reviewing the enquiry, which "may or may not lead to an offer for the whole or partial sale of the company".
The platform was launched in 2007 by Japan's Nomura through inter-agency broker Instinet, to take on traditional exchanges such as the LSE and Deutsche Börse in the wake of MiFID.
Instinet now has a 34% stake, with a group of 12 banks and trading firms - including Citi, Goldman Sachs, UBS and Citadel - holding the rest of the shares.
Since launch, the MTF has used faster trading technology and lower fees to attract market share from incumbents, moving into profit this year. Last month, reporting quarterly figures, it claimed to have attracted 26.7% of trading in FTSE 100 shares and 20.2% of DAX 30 trading for the thee months.
Nasdaq OMX and Deutsche Börse have both been touted as potential bidders for the platform, with a price in the region of $200 million to $300 million mooted. The LSE has already taken over an MTF rival, buying a majority stake in the Turquoise platform last year.
However, a late afternoon report by Bloomberg citing two people "familiar with the situation" names Bats Trading as the mystery suitor. A deal between Chi-X and Bats Europe would unite the two largest MTFs to emerge in Europe since the MiFID market shake-up in 2007.
John Woodman, chairman, Chi-X Europe, says: "Any future offer must be examined and assessed to ensure that it fully values the company and also we must take into consideration the strategic interests of shareholders/stakeholders."