Gain-on-sale margins for mortgage originations declined for lenders during the first quarter of 2013, according to industry analysts, but a number of factors appear likely to keep the margins this year well above historical levels. Core gain-on-sale margins for the major banks fell to 2.9 percent in the first quarter of 2013, according to estimates by Credit Suisse Securities, down from 3.3 percent in the previous quarter and from a high of 3.5 percent in the third quarter of 2012. The analysts warn ...