国际清算银行-将资产负债表政策纳入货币政策条件（英）-2025.7_41页_3mb

报告分析总结

研究主题与目的

The Working Paper introduces a Monetary Policy Conditions Index (MCI) that integrates conventional monetary policy (short-term interest rate) and unconventional measures (central bank balance sheet size) into a unified framework. The goal is to provide a consistent measure of monetary policy stance across different regimes (including periods with or without the effective lower bound or ELB).

Key Features

1. MCI Definition: MCI is defined as a weighted average of the short-term interest rate (( m_t^1 )) and the central bank balance sheet size (( m_t^2 )), scaled by nominal GDP. ( m_t^1 ) reflects the flow effect, while ( m_t^2 ) captures the stock effect (central bank's asset purchase impact).
   Formula: ( m_t = b \cdot m_t^1 + (1 - b) \cdot (- m_t^2) ), where ( 0 < b < 1 ) is estimated.
   Negative sign before ( m_t^2 ) reflects opposite effects of higher rates vs. larger balance sheets.
   A re-normalized version ( \tilde{m}_t ) is suggested for comparison.

2. Estimation Method: Uses a Bayesian Vector Autoregression (BVAR) framework with sign restrictions to identify structural shocks (demand/supply/risk aversion/monetary policy shocks).
   Estimation focuses on ( b ): Bayesian approach incorporates literature priors (e.g., estimates from prior studies linking balance sheet reduction to equivalent rate hikes). Data is crucial due to limited historical experience and complex interactions.

Main Findings and Contributions

1. Evaluating Unconventional Policy Effectiveness:

   • Large-scale central bank asset purchases (especially during GFC and post-pandemic) have had a significant accommodative influence, keeping financial conditions easier even when rates are boosted from ELB.
   • Phase out of these policies (i.e., quantitative tightening - QT) has contributed to higher post-pandemic inflation and seen its effects linger for 18-24 months.
   • MCI provides new insights through impulse response functions and historical decompositions, showing policy actions partly explain financial condition swings (loosev/s tightenings) and increases/decreases in output/inflation.

2. Replacing Shadow Rate: MCI supersedes the shadow rate approach because the shadow rate loses validity when balance sheet policy remains active concurrently with interest rate adjustments. MCI consistently captures the stance of monetary policy including balance sheet effects away from the ELB.

3. Robustness and Extensions:

   • MCI shows robustness using alternative balance sheet proxies (like duration-adjusted measures, adjusting for bond supply).
   • It can be effectively used in high-frequency identification of monetary policy shocks, improving instrument strength.
   • The framework can be extended to incorporate time-varying substitutability and to consider neutrality of balance sheets under ample reserve systems, decomposing effects into liquidity and stock effects. A global version also highlights international spillovers.

4. Policy Stance Considerations: Under an "ample reserves" system, balance sheet policies have become an integral tool alongside interest rates. QT cannot be underestimated in impacting financial conditions or inflation, possibly altering the neutral rate path.

Policy Implications & Conclusion

• Central banks need to anticipate the persistence of very accommodative balance sheet policies even after scaling back the emergency impulse.
• Implications of balance sheet effects need to be factored into both forward guidance and potential future interest rate setting. MCI provides a simpler framework to assess the overall monetary policy stance more comprehensively.

Overall: This paper successfully develops a practical MCI that offers a unified, robust measure to assess the stance of monetary policy impacting an economy, integrating interest rate and balance sheet policies, and valuable for guiding policymakers through periods of significant balance sheet management.