Carolyn Walton was promoted to vice president and treasurer of Blue Cross-Blue Shield of Michigan, Detroit. Ms. Walton is responsible for investment of the company's $784 million defined benefit and $436 million defined contribution plans and investment of some insurance and corporate assets. She replaced Brenda Ball, who left the firm at the end of October. Ms. Walton was director of treasury services at the company. It could not be learned whether she will be replaced.