Real estate investment portfolios of financial institutions have seen dramatic changes over the last three decades or more. Historically such property investment decisions have been seen within a portfolio diversification paradigm that has sought to balance risk and return. This paper considers the role of the supply of assets in the determining and constraining the UK institutional portfolio. The supply of real estate assets not only expands during development booms but has also been transformed as the spatial structure of cities and property forms adapt to cars and the ICT revolution. The research examines long term temporal patterns n the development of new forms of real estate and the change to the institutional portfolio as exemplified by the IPD database. It considers to what net investment changes are driven by the returns of individual sectors or vice versa based on Granger Causality tests. It also assesses to what extent investment patterns can be explained in terms of portfolio theory.