Moody's Investors Service has downgraded the debt and financial-strength ratings of the parent of Chicago-based Blue Cross and Blue Shield of Illinois. Moody's said Health Care Service Corp., the nation's fourth-largest health insurance company, has been hampered by higher-than-expected medical costs driven by increased unemployment and layoffs that reduced membership. Health Care Service has 12.5 million health plan members and operates Blue Cross and Blue Shield plans in Illinois, Texas, Oklahoma, and New Mexico.
