CME Group Inc., the world's largest futures market, dropped from a record close in pre-Christmas stock trading after a dozen brokerages said they would start a competing exchange. The track record of would-be rivals suggests the shares may soon rebound. Bank of America Corp., Barclays Plc, Citadel Investment Group LLC, Citigroup, Credit Suisse Group, Deutsche Bank AG, eSpeed Inc., Getco Holding Co., JPMorgan Chase & Co., Merrill Lynch, Peak6 Corp. and Royal Bank of Scotland Group Plc are all investing in the electronic market, according to a statement. The exchange, as yet unnamed, plans to start next year by taking on the Chicago-based company in U.S. Treasury contracts. Even Eurex AG, Europe's biggest derivatives exchange, failed to crack that market. Eurex sold a 70 percent stake in its U.S. futures unit after a two-year effort to compete with the Chicago Board of Trade, now part of CME, in Treasury futures. All-electronic markets started previously by ESpeed and BrokerTec Global LLC, now a unit of ICAP Plc, were also unsuccessful.