Shares of IntercontinentalExchange Inc. rose 1.8 percent to $154.50 while CBOT Holdings Inc. advanced 2.8 percent to $212 before the opening bell on Friday after the Chicago Mercantile Exchange Holdings Inc. said it agreed to increase its merger offer for CBOT ahead of a shareholder vote on Monday.

IntercontinentalExchange, or ICE, an Atlanta-based exchange whose strength has been energy derivatives trading, made a higher bid for CBOT in March that was rejected by CBOT's board.