포트폴리오이론에 근거한 임대보증금에 대한 운용소득가설의 재해석

Security deposit is regarded as one of the most distinctive characteristics of Korean real estate market, because the amount of security deposit compared to that of monthly rent is much larger than those in other countries. In the past, Interest-Seeking Hypothesis which suppose most landlords pursue interest income from security deposit was widely accepted. Recently, however, Leverage Effect Hypothesis which suppose most landlords use security deposit as a way of leverage is prevailing. The long-term gap between conversion rate and market interest rate changed such belief on the function of security deposit. This study constructs theoretical inference on Interest-Seeking Hypothesis in terms of Portfolio Theory which considers risk as well as return, and explains the behavior of investors who receive security deposit at high conversion rate and reinvest it at low interest rate. Firstly, considering the rent-security effect of security deposit, interest-seeking behavior could maximize the utility of investors who have strong risk-averse tendency. The interest-seeking portfolio is located at the most low risk low return position on the Investment Opportunity Line. Secondly, conversion rate, the opportunity cost of security deposit, is not necessarily equal to reinvestment rate. So capturing the dominant function of security deposit by observing market conversion rate is impossible. Finally, the higher tenant risk and risk-averse tendency of investors are, the more interest-seeking behavior would be pursued.