. as of december 31 , 2012 , the noncredit portion of impairment recorded in accumulated other comprehensive income for non-agency residential mortgage- backed securities for which we have recorded an otti credit loss totaled $ 150 million and the related securities had a fair value of $ 3.7 billion . the fair value of sub-investment grade investment securities for which we have not recorded an otti credit loss as of december 31 , 2012 totaled $ 1.9 billion , with unrealized net gains of $ 114 million