An anonymous block trade matching system which allows users that who wish to cross large blocks of stock to submit orders, or indications of interest, with the option of utilizing market peg benchmarks or future price cross benchmarks. Orders submitted may be subject to minimum thresholds, including a threshold requiring that the order represent ‘X’ % of average daily volume. After submission of a firm order in the system, an alert is generated to provide the order data to other users with potential to cross the order. Visibility of order data by other users may be restricted based upon a data interaction group to which the ordering user or the other user belongs. The system provides users viewing order data with a capability of communicating with the submitting user via a restricted two-way messaging interface.