In a mortgage market thoroughly dominated by agency-eligible home loans, a handful of boutique products such as no-downpayment loans, “energy-efficient” mortgages and peer-to-peer mortgages are trying to gain a foothold. Navy Federal Credit Union has been offering a no-downpayment mortgage since 2010, and officials said demand for the “HomeBuyers Choice” product has grown this year. The credit union holds originations of the no-downpayment loan in portfolio. The product is available for balances ...