Mortgage Guaranty Insurance Corp. – along with the rest of the private MI industry – posted a dramatic increase in new business during the first quarter of this year, according to a new Inside Mortgage Finance ranking and analysis. MGIC reported $13.12 billion in new private insurance written, over half of it coming through $6.7 billion in bulk transactions. The company’s first-quarter new business was up 36.4 percent from the previous period and 78.3 percent