The ICE offer values Cbot at $187.34 per share, a 12.8 per cent premium to Board of Trade's closing share price on Wednesday, and 10.5 per cent higher than the pending merger value offered by CME. Cbot shareholders would hold the majority stake in the combined company, with a 51.5% share.

The all-electronic ICE specialises in commodities futures and transactions in the over-the-counter market. The company says its offer will protect and grow the Cbot metals complex and promises $240 million annually in transaction benefits. ICE also offers a clearing option following its recent takeover of the New York of Board of Trade.

Crucially, ICE believes no significant antitrust or other regulatory risks exist in a combination with Cbot and a transaction could be completed quickly.

Jeffrey Sprecher, chairman and CEO of ICE, comments: "The Cbot board of directors has the opportunity to achieve a transaction that offers a considerable premium to the pending CME transaction and, at the same time, secures the Cbot's position as a leading independent global derivatives complex based in Chicago."

The move comes a day after the CME laid out a more agressive timescale for post-merger integration with Cbot.

Brad Bailey, senior analyst at Aite Group observes: “If nothing else, the bid puts pressure on CME to move its attention away from post-merger planning to try to get the deal done. In many circles, where concern for the CME/Cbot combination caused the greatest stress, this move by ICE will be seen as quite positive. The question is-who else is waiting in the shadows to step forward and pick up this Chicago gem?”

Separately, Reuters is reporting that ICE has agreed to buy an eight percent stake in India's National Commodity & Derivatives Exchange from ICICI Bank for close to $40 million, citing anonymous sources close to the transaction.