Fractional cointegration and the term structure

According to the expectations theory of the term structure of interest rates, the yield spread between long-term and short-term interest rates is an optimal predictor of future changes in short rates over the long-run. Results concerning the empirical validity of this hypothesis are not unanimous. These contradictions may be due to the fact that the traditional concept of cointegration is too restrictive. We refer here to the concept of fractional cointegration introduced by Granger (1986). We study the expectations theory by testing for the existence of a (fractional) cointegration relationship between short-term and long-term interest rates. There is evidence of fractional cointegration between interest rates for the G7 countries, with the exception of Germany.First version received: July 2002 / Final version received: July 2003We thank two anonymous referees for very helpful and detailed comments.