The parent of the Chicago Board Options Exchange has held talks with a number of governors and state officials about a possible move of its headquarters to another state after Illinois raised its tax rate, providing another challenge to the city's status as the self-styled "derivatives capital of the world." January's tax increase is seen increasing CBOE Holdings Inc.'s (CBOE) state tax bill by a quarter. Chicago-based CME Group Inc. (CME), the world's largest futures exchange operator, is also talking about relocating its headquarters. "We've had a series of meetings with people in this state and outside this state," said...