Two Standard & Poor's executives who had key roles during the financial crisis are leaving the credit rating firm and its corporate parent - the latest stage in the company's gradual makeover. Vickie Tillman, who was an S&P EVP until 2009, is in talks to leave S&P parent, McGraw-Hill, where she currently is head of global sustainability business development.  Joanne Rose, who from 1999 until 2008 had run the S&P team that rated mortgage securities and other structured-finance deals, will leave in January.  Some of those ratings are now being investigated by U.S. prosecutors and securities regulators. Tillman ran S&P's ratings business ... for a decade and reported directly to the firm's president.  She emerged as a public face of the firm in the wake of crisis, and appeared repeatedly before congressional panels to defend S&P against allegations its ratings on securities linked to home loans helped deepen the downturn. S&P President Doug Peterson, who joined S&P in September, is trying to forge a new identity for the firm and restore a reputation tarnished by the crisis.  The former Citigroup banker seeks to enhance firm internal controls while championing analysts' independence.  However, some former S&P analysts say such changes, by Mr. Peterson and his predecessor, have been slow going. Apparently, many of their former colleagues - who oversaw ratings on complex mortgage-linked deals - are still at the firm, even though investors, regulators and lawmakers have called for wholesale changes. In spite of such criticism, S&P and rivals Moody's Investors Service and Fitch Ratings remain the dominant players in the business of rating everything from corporate and sovereign debt to asset-backed securities. Mr. Peterson succeeded Deven Sharma in September.  Since then, S&P replaced its chief credit officer, Mark Adelson, in early December.  Mr. Adelson, who joined S&P in 2008, was given the mandate of making it harder for debt-issuers to earn a "AAA" rating from the firm.   The firm also announced earlier this month that David Jacob, who succeeded Ms. Rose as S&P's structured finance chief, would step down at the end of the year. [WSJournal - 12/28/11]