1. A system for trading a list of securities, comprising: an algorithmic trading facility coupled with at least one destination including at least one alternative trading system (ATS) and with a plurality of trading clients via an electronic data network, said algorithmic trading facility configured to receive a trade request to trade a list of securities from a trading client, said request including user defined trading constraints, and said list of securities including at least two different securities, to generate and transmit a plurality of trade orders to said at least one ATS based on trading data related to said destinations, said trade list, and said trading constraints, to identify a set of executed trades corresponding to said plurality of trade orders, to calculate a trade imbalance based on the set of identified executed trades and said trade list, to determine whether said trade imbalance exceeds said trading constraints; and to reallocate one or more of said submitted orders based on said determining step.