A system and associated method if provided for rebalancing a client's portfolio of securities. A client device is provided with a client interface that is configured to receive a client's rebalance order which includes fraction shares. A host server is coupled to the client device and executes logic resources for carrying out transactions for a client. A pricing engine and an inventory account are included. A targets engine determines a target number of long and shorted shares of a security to be held by the inventory account. A trading engine that is configured to process a client's rebalance order of a client's portfolio. The client receives a list of current positions, selects a share-weighted portfolio, chooses an alternate weighting, and decides to: (i) add funds, (ii) remove funds or (iii) rebalance the share-weighted portfolio.