摘要 : This article examines how and to what extent large-scale government bond purchases in the Bank of Japan's monetary policy affected two components of long-term interest rates over the period 2009-2015. The article divides market yi... 展开 This article examines how and to what extent large-scale government bond purchases in the Bank of Japan's monetary policy affected two components of long-term interest rates over the period 2009-2015. The article divides market yields on popular 5 and 10-year government bonds into future policy-rate expectations with uncertainty and a specific type of term premia required by investors for the bonds' demand/supply imbalances, by using overnight index swap rates as a proxy for the former. The Bank of Japan augmented the purchases substantially by starting Quantitative and Qualitative Monetary Easing (QQME) in 2013. The QQME became impactful in the sense that it encouraged investors to improve the first component whilst reducing the second component. These appeared mainly as persisting announcement-effects - upward level shifts of the expectations and downward ones of the term premia. The reduction of term premia was much greater for the 10-year maturity than for 5-year one and strengthened after an additional expansion of the QQME in 2014. The QQME is estimated to have enhanced 5-year sovereign bond yields by 11.9 basis points (bps) a month on average whilst reducing 10-year ones by 8.3 bps. The impact on the 5-year yields turned to be negative after the QQME expansion. 收起