Mortgage Guaranty Insurance Corp. regained its customary position as the top private mortgage insurer in the market during the second quarter of 2006, as the red-hot bulk MI business began to cool off a bit, according to a new Inside Mortgage Finance ranking and analysis.Overall, the volume of new primary MI coverage increased by 3.1 percent from the first to the second quarter, with the seven private companies expanding their combined share of this business to a record 79.4 percent...