A flat yield curve and increased regulatory warnings appear to be having little impact on the still growing popularity of so-called alternative mortgage products in both the agency and non-agency mortgage markets. Over a third of new mortgage originations in the first quarter of 2006 came from interest-only loans, option ARMs, 40-year amortization periods and balloon loans, according to the Inside Mortgage Finance MBS Database. A substantial portion of these loans – as well as… [One data table included]