Ambrose et al (2007) showed that when few REITs were included into the S&P general market indices in 2001, other REITs that are not included in the indices became more correlated with the market index returns. Whilst Ambrose et al (2007) examine information spillovers between two assets in the same category (indexed REITs versus non-indexed REITs), this study tests the information spillover effects of the REIT’s index inclusion on a non-overlapping category of assets represented by non-index real estate operating companies (REOCs). Using both the US and Singapore data, we found that the non-index REOC returns became more correlated with the general market index returns after the REIT’s index inclusion event in the US, but the spillover effects on REOCS were weaker in Singapore market. We also use the REIT IPO events in Singapore to test if spillovers could be induced by other market risks, and our results remain the same, where increases in beta were only observed in REIT market, but the changes were insignificant in REOC betas after the IPO events. However, we also found significant captive relationships between REOCs and their sponsored REITs, which imply that REOCs could use REIT IPOs as a “de-risk” vehicle to reduce systematic risks of the sponsor REOCs.