This paper develops a simple new methodology to test for asset integration and applies it to the Japanese stock market as represented by the Tokyo Stock Exchange (TSE). The technique is tightly based on a general intertemporal asset-pricing model, and relies on estimating and comparing expected risk-free rates across assets. Expected risk-free rates are allowed to vary freely over time, constrained only by the fact that they are equal across (risk-adjusted) assets. Assets are allowed to have general risk characteristics, and are constrained only by a factor model of covariances over short time periods. The technique is undemanding in terms of both data and estimation. I find that expected risk-free rates vary dramatically over time, unlike short-term interest rates. Further, the TSE does not always seem to be well integrated in the sense that different portfolios of stocks are priced with different implicit risk-free rates.
Keywords: Stock prices; Risk; Portfolio
Views expressed in the paper are those of the authors and do not necessarily reflect those of the Bank of Japan or Institute for Monetary and Economic Studies.