Abstract: The Secret Key-Based Counterparty Matching Engine Apparatuses, Methods and Systems (“SKCME”) transforms client key message, order placement input inputs via SKCME components into order placement output outputs. A matched key is determined and used to generate a set of cross times and a set of cross venues for a security identifier. Orders associated with the security identifier are obtained from counterparties and are assigned a scheduled cross time from the generated set of cross times and a scheduled cross venue from the generated set of cross venues. The orders are sent for execution at the scheduled cross venue at the scheduled cross time.