▁proceed s ▁and ▁usually ▁is ▁able ▁to ▁buy ▁back ▁the ▁mort g age ▁for ▁a ▁lower ▁price ▁than ▁the ▁sale ▁price . ▁The ▁difference ▁in ▁the ▁prices ▁is ▁called ▁the ▁drop . ▁ ▁The ▁value ▁of ▁the ▁drop ▁plus ▁interest ▁earned ▁on ▁the ▁proceed s ▁of ▁the ▁sale ▁less ▁the ▁forg one ▁interest ▁and ▁principal ▁pay ments ▁on ▁the ▁mort g age ▁is ▁considered ▁the ▁roll ▁special ness ▁or ▁finan cing ▁advantage . ▁ ▁With ▁rep urchase ▁agre ements ▁exactly ▁the ▁same ▁security ▁is ▁returned ▁to ▁the ▁invest or , ▁while ▁with ▁doll ar ▁roll s ▁the ▁invest or ▁bu ys ▁a ▁substantial ly ▁similar — but ▁not ▁necessarily ▁identical — security . ▁ ▁This ▁difference ▁produces ▁complex ▁results ▁under ▁certain ▁areas ▁of ▁the ▁United ▁States ▁In ternal ▁Re venue ▁Code . ▁ ▁D ollar ▁roll s ▁help ▁invest ors ▁achieve ▁various ▁object ives , ▁such ▁as ▁stay ing ▁inv ested ▁in ▁mort g ages ▁while ▁ear ning ▁a ▁trad ing ▁spread . ▁ ▁Like wise , ▁if ▁an ▁invest or ▁faces ▁oper ational ▁or ▁delivery ▁obst acles ▁with ▁respect ▁to ▁a ▁certain ▁mort g age - back ed ▁security , ▁a ▁doll ar ▁roll ▁may ▁help ▁the ▁invest or ▁retain ▁the ▁economic ▁expos ure ▁while ▁avoid ing ▁the ▁oper ational ▁difficulties . ▁ ▁References ▁ ▁Category : Der iv atives ▁( fin ance ) <0x0A> </s> ▁Os min ia ▁is ▁a ▁genus ▁of ▁moth s ▁in ▁the ▁family ▁S esi idae . ▁ ▁Species ▁Os min ia ▁fen us ae form is