A method and system for forecasting the transaction cost of a portfolio trade execution that may be applied to any given trade strategy or an optimal trade strategy that minimizes transaction costs. In preferred embodiments, a server comprises one or more computers that act as an automated forecaster whereby it accepts user-defined input variables from customers and generates a transaction cost estimation report based on those variables. The server is programmed with specific transaction cost estimation and optimization algorithms that model the transaction costs of a specific trade execution based on the user's trading profile and market variables.