The US investment bank has been taken on to help it with a planned initial public offering (IPO), scheduled for April, taking advantage of current demand for futures and options trading.
The exchange has not yet officially decided where it will list its shares, although some market observers suggest that the hiring of Citigroup could mean that a US listing is being considered.
The Montreal Exchange has seen trading volumes increase significantly in recent months and years.
Earlier this month, an increase in volumes of 41.3 per cent was reported for 2006, with a record 40.5 million contracts recorded.
The exchange is expected to have a market capitalization of CAN$1 billion ($844 million), analysts say.