Regulators remain divided about how to create a better system for credit rankings in the $43 trillion global debt market. The Dodd-Frank Act, signed into law last year to overhaul financial regulation, requires government agencies to replace ratings with another standard for creditworthiness, without providing a solution. "That people have been focused on it for three years and haven't come up with an answer tells you it's not an easy answer," said Gary Witt, a former Moody's managing director who's an assistant professor of statistics and finance at Temple's Fox School of Business. "There's just not a good alternative."