Relationship between Idiosyncratic Risk and Total Rate of Return: Focused on Seoul Office Market

In this paper, the excess ROI(Return on Investment) and SCL(Security Characteristic Line) ofthe Seoul office market by region are driven based on the ROI of the Seoul office market and CD(91days) rate of return(quarterly), then with this, idiosyncratic risk is extracted, and the idiosyncraticrisk-excess rate of return on investment relationship in the office market by district is analyzed. Finally,the results driven from this study is as follows; 1) Regarding the idiosyncratic risk-excess ROIrelationship by district in Seoul, the CBD shows a low risk-low return tendency, and the YBD showsa high risk-high return. Moreover, in the case of total risk-return, the risk of the ETC is higher thanthat of the GBD, but the idiosyncratic risk is lower than that of the GBD, showing different risk-returncharacteristics depending on the type of risk. 2) As to the idiosyncratic risk-excess investment returnrelationship by district in Seoul, although all districts are markets affected by idiosyncratic risk, thegrowth rate in excess return compared to idiosyncratic risk are different. 3) The excess return oninvestment/idiosyncratic risk by district differs according to the growth rate in office buildings’ salesprice, and no change in the excess return on investment per idiosyncratic risk due to the increase inNOI could be confirmed in all district but YBD. Finally, this paper is meaningful in that it verifies theexistence of idiosyncratic risk in the Seoul office market and the statistical significance betweenidiosyncratic risk-return on investment, and derives related implications through a comprehensiveanalysis relevant to the market situation.