MEMX LLC, the upstart exchange operator backed by some of Wall Street’s biggest names, is combining with BOX Options Market in a deal that values the merged entity at roughly $2.3 billion. The twist: Canada’s TMX Group walks away with the keys to the castle, securing approximately 59% ownership of the newly formed MEMX Group.
TMX is putting up around $800 million in cash and rolling its existing stake in BOX to lock in that controlling position. The remaining ownership stays in the hands of MEMX’s original backers, including Jane Street, Morgan Stanley, Citadel Securities, Virtu, and Optiver, who are all rolling equity into the new structure.
What the combined entity looks like
MEMX Group will operate three US options exchanges alongside an equities exchange and a technology business.
In 2025, MEMX and BOX generated combined revenue of approximately $280 million, with adjusted EBITDA coming in around $134 million. That’s roughly a 48% EBITDA margin.
