A user terminal for communicating with a computer server is operated on behalf of a first user (a second user terminal is operated on behalf of a second user). The user terminal transmits to the computer server pre-trade information including an order and receives first offset information that indicates a first price offset value, which is different from a second price offset value sent to the second user terminal. The terminals receive a single message from the server that indicates a market price but does not include the first price offset value or the second price offset value. The user terminal modifies the market price using the first price offset value to obtain a first actual price different from a second actual price corresponding to a modification of the market price based on the second price offset value.