Policymakers should replace Fannie Mae and Freddie Mac with mandatory mortgage insurance and a catastrophic guaranty from the federal government, according to a new paper from Promontory Financial Group, a consulting firm. The paper was prepared at the request of Genworth Financial and Promontory said the mortgage insurance firm didn’t influence the recommendations. Under Promontory’s proposal to reform the government-sponsored enterprises, private entities would both issue and guarantee their own mortgage-backed securities, private MI would be required on a loan-level basis for mortgages securitized in the new system, and a government agency would provide a back-up guaranty on the MBS payable only upon default by the MBS issuer. “Our proposal is...