NYSE in talks with a rival regarding a merger

It could be any number of exchanges, so speculation is mounting.

New York Stock Exchange operator NYSE Group Inc. confirmed that it is holding preliminary merger talks with more than one exchange-industry participant, according to a regulatory filing.
The exchange made the disclosure in an amended filing in preparation for its secondary stock offering, expected early next month. Two people briefed on the bellwether offering -- the first by NYSE to the public -- said they expected NYSE to hold a roadshow starting around April 24, a sign that NYSE wants to finish that deal and focus fully on a possible merger. NYSE will hold an analyst meeting this coming Friday, after it releases earnings Wednesday.

Here is the link to the WSJ article