Private mortgage insurers represented by the Mortgage Insurance Companies of America wrote $4.9 billion in new business September, down 29% from $6.9 billion the same month a year ago. Last month, MICA wrote $5.7 billion in new business. MICA reported its member companies — including Genworth Mortgage (GNW), Mortgage Guaranty Insurance Corp. (MTG), Radian Guaranty (RDN), and Republic Mortgage Insurance Co. (ORI) — had $477 billion in primary insurance in force in September. That is down 38% from nearly $773 billion in September 2010. Defaults outpaced loan cures in September with MICA reporting that insurers under its umbrella had 38,719 loan defaults insured by the industry, down 41% from 65,481 the same month a year ago. The organization reported 31,129 cures, down 46% from 57,720 a year ago. Almost 25,000 borrowers used private mortgage insurance to buy or refinance a home, a fall of 24% from 32,554 last September. Member companies received nearly 28,000 applications, a fall of 30% from nearly 40,000 applications the same month a year ago. Today's news of a drop from a year ago in all categories — new business, applications received, defaults, cures, primary insurance in force and the number of borrowers who used private mortgage insurance — comes a week after the Federal Housing Finance Agency removed several key barriers to the Home Affordable Refinance Program to allow more underwater borrowers to move into lower-rate mortgages. On the same day, Genworth said it would participate in the modified HARP and MICA endorsed the changes. Write to Justin T. Hilley. Follow him on Twitter @JustinHilley.