Private mortgage insurance issuance has declined 3 percent since the end of 2002, forcing private MIs to expand their coverage into nontraditional products such as subprime, Alt A and second mortgages, according to a new report from Fitch Ratings. “Fitch believes that possibly no other sector of the mortgage origination process has been more adversely affected by the changes taking place in that industry than the private U.S. mortgage insurers, particularly with respect to their…