CME Group, the world's largest financial exchange company, hosts trading of contracts that derive their value from an underlying commodity or event for things such as gold, oil and wheat. Investors use these contracts to shelter their investment portfolios from swings in interest rates or fluctuations in the stock market.

The New York Mercantile Exchange specialises in trading of energy and metals contracts, and has already partnered with CME to list some contracts on CME's electronic exchange.

Under the deal, shareholders of Nymex Holdings Inc. would get $3.4 billion in cash and $6.08 billion in stock. The proposed combination was first announced earlier this year.

Chicago-based CME is paying 12.5 million shares - valued at $6.08 billion based on the stock's on Friday closing price of $486.05.

Nymex holders will receive 0.1323 Class A shares of CME Group and $36 in cash for each share outstanding.

Priced at $100.30 per share, the deal announced Monday is valued at about $9.48 billion, based on roughly 94 million shares outstanding at Feb 20. Shareholders of Nymex will own about 19 per cent of the combined company.

'This strategic combination with Nymex ... continues both of our companies' traditions of finding innovative ways to create value for our customers and shareholders,' CME Group Executive Chairman Terry Duffy said in a statement.

Monday's agreement must still be approved by regulators and shareholders of the two exchanges. The companies said they expect the deal to be complete in the fourth quarter.

Shares of CME fell $22.73, or 4.6 per cent, to $463.82 in morning trading Monday. Shares of Nymex fell $6.09, or 6.4 per cent, to $89.25. -- AP