We examine daily cross-market return interactions and downside risk between a US REIT returns index and the return indexes of twelve international REIT markets. These relationships are investigated for a period of normal REIT market conditions as well as for periods of inflating and collapsing REIT prices. We find that US REIT returns are contemporaneously correlated with other REITs most strongly during the bubble and crash market conditions where the US REIT market is an almost unilateral transmitter of returns. We also find that the Value at Risk (VaR) of the least capitalized REIT markets is proportionally higher during base/normal market conditions but that the largest REIT markets have the highest VaR contribution during the crash (financial crisis) period. Overall, our evidence indicates that REIT market risk shifted to the largest REIT markets and that diversification benefits eroded considerably during turbulent market conditions.