The Intercontinental Exchange increased terms of its offer to buy the Chicago Board of Trade in an attempt to win over skeptical shareholders.

It told CBOT shareholders yesterday that its offer is now 20 percent higher than the competing offer from the Chicago Mercantile Exchange. The new offer from the I.C.E. includes more cash for CBOT members.

The move came just a day after antitrust regulators gave the nod to the Chicago Mercantile Exchange to go ahead with its plan to combine with CBOT. The C.M.E. has argued that its offer is superior because it doesn't have the same integration issues that the I.C.E. would face if it combined with CBOT, according to the Financial Times.

The move will put likely put pressure on the C.M.E. to raise its offer as well.