Abstract: A system and method for trading large blocks of securities with controls for limiting trading under conditions of aggressive pricing are described The system and method are preferably used by a buyer or seller in the electronic trading of securities in dark pools, e.g., and ATS or ECN, that include algorithmic trading or other computer-based programmed trading. Preferably, the system and method will be automatically activated to control trading volume when the price of a security being traded becomes aggressive and priced outside of the trader's target price instructions.