Ginnie Mae plans to allow lenders to securitize single loans starting in July, a policy change that would help small lenders be more competitive when doing business with the agency and with the Federal Housing Administration. The FHA does not make loans but insures certain lenders against losses should borrowers default. The agency has played a key role in propping up the housing sector since the mortgage market meltdown. Mortgage lenders working with the FHA often bundle the loans they make into securities and sell them to investors. Ginnie Mae guarantees those securities so that investors continue to get their principal and interest if loans go bad or lenders are unable to make payments to investors.