Fannie Mae and Freddie Mac last week both “de-listed” PMI Mortgage Insurance Co. as an eligible private MI, a further blow to a private MI business that has been driven to the brink by the housing market collapse. Republic Mortgage Insurance Corp. was forced to stop writing new business this week as North Carolina regulators declined to extend a waiver of risk-capital ratios under which it had remained in the market. Together, PMI and RMIC accounted...