OK try this version

=IF($B15<=$B$4;SUMPRODUCT((SettlDate_Blotter=$B15)*(Securities_Blotter=HM$13);Contracts_Blotter;TradePrice_Blotter;1/(1+daily interest rate*(SettlDate_Blotter<>TradeDate_Blotter))/IF(BG15=0;1;BG15);0)