A method of computing a real estate derivative index value includes : selecting asking rent data; selecting lease rent data; and combining the selected asking rent data and the selected lease rent data to form the index value. The method may further include further combining the combined data with a value representative of general market conditions; forming a composite index of data from plural markets; or computing the index at the end of a time period as : [in-line-formulae]Δ FKI or as Δ RP+Δ CPI+Δ FKI.[/in-line-formulae] The method may further include trading based on the index by deriving a trade value from the index value, and executing a trade based on the derived trade value. The method may be carried as instructions on a machine-readable medium and may be carried out using a computer for part or all of the method.