General Motors Corp. (GM) had another bad day on Tuesday as its partially owned subsidiary GMAC Financial Services announced a major loss for the third quarter. GMAC is co-owned by GM and Cerberus Capital Management, a private-equity firm. While its original role was to finance the purchase of General Motors autos, over the years it has evolved into a major mortgage lender and insurance company. The company's losses have come from both its subprime lending and vehicle leasing operations and GMAC...