1. A system for conducting index or theme based basket security transactions, comprising: a client device with a client interface that in operation is configured to receive an index or theme based basket client order; a host server coupled to the client device which in operation executes logic resources for carrying out transactions for a client; a pricing engine; an inventory account; an targets engine; a trading engine that in operation is configured to process the client index or theme based basket order as a single order, wherein the trading engine enables the trading of fraction shares in real time as well as reduces a frequency of orders sent to market by executing principal trades against an inventory account.