HousingWire reports that Moody’s Analytics says the federal government should do more to help the 14 million underwater mortgages before falling home prices lead to another downturn in the housing market.  Analyst Mark Zandi says plummeting home values could be sufficient to induce more underwater borrowers to hand their keys over to the lender, especially if they can rent something suitable for less than their mortgage payment.  Half of the 14 million owe 30 percent or more than the house is actually worth.  Zandi suggests lawmakers enact more home refinancing options that reduce the principal more aggressively.