Lehman Brothers posted a hefty 118 percent increase in its underwriting of non-agency MBS from 2001 to 2002, finishing the year as the top investment banker in the field. Lehman accounted for $61.3 billion in non-agency MBS underwriting, according to a new Inside MBS & ABS analysis that credits each underwriter for the share of the deal credited to them in securities disclosures. That gave