Understanding Extended ISLM Model Dynamics

Aug 24, 2024

Lecture Notes on Extended ISLM Model

Overview

  • Focus on extending the ISLM model along two dimensions: nominal vs. real interest rates and credit spreads.
  • Importance of understanding these concepts for the upcoming quiz and overall comprehension.

1. Nominal vs. Real Interest Rates

Definition

  • Nominal Interest Rate (i): The stated interest rate in terms of dollars (e.g., 10% on a bond).
  • Real Interest Rate (r): The interest rate in terms of a basket of goods, adjusted for inflation.

Key Points

  • Historically, the assumption was no inflation (fixed prices), leading to no distinction between nominal and real rates. However, inflation is typically positive.
  • Impact of Inflation: When inflation is expected to be nonzero, the real interest rate will differ from the nominal interest rate.

Importance of Real Interest Rate

  • Real rates impact private sector decisions, especially regarding investment in physical assets.
  • Investment decisions focus on the real rate since that reflects the true cost of borrowing adjusted for future inflation.

Calculation of Real Interest Rate

  • Derived from nominal interest rate and expected inflation:
    • ( r \approx i - \text{Expected Inflation} )

2. Credit Spreads

Definition

  • Credit Spread (X): The difference between the interest rate on risky corporate bonds and the risk-free rate (e.g., U.S. Treasury bonds).

Key Points

  • Corporate bonds typically carry risk, requiring a premium over the risk-free rate due to potential default risk.
  • Increased credit spreads during financial crises and economic downturns reflect heightened risk perception.

Factors Influencing Credit Spread

  1. Probability of Default (P): Higher perceived risk leads to higher credit spreads.
  2. Risk Aversion: Investors may require higher compensation for holding riskier assets during uncertain times.

3. Integrating Extensions into the ISLM Model

Modifications

  • Investment Function: Now depends on real interest rates adjusted for credit risk (X) rather than just nominal rates.
  • Introduced parameters for expected inflation and credit spreads into equilibrium analysis.

Economic Implications

  • When expected inflation rises or credit spreads decrease, it acts similarly to an expansionary monetary policy, shifting the ZZ curve upward.
  • Conversely, during economic downturns (e.g., Great Recession), rising credit spreads and falling expected inflation shift the IS curve inward, reducing investment.

4. Historical Context and Recent Events

  • 2008 Financial Crisis: Notable shift in real vs. nominal interest rates, with real rates surpassing nominal rates due to plummeting expected inflation.
  • COVID-19 Pandemic: Initial drop in interest rates, rapid recovery of expected inflation, and rising credit spreads.
  • Current Situation: Challenges for the FED as nominal rates rise but real rates do not keep pace due to fluctuating expected inflation and credit spreads.

FED’s Response Strategies

  • Large Scale Asset Purchases: The FED engaged in purchasing corporate bonds to stabilize financial markets and reduce credit spreads during crises.
  • Effects on Financial Conditions: Central banks aim to lower borrowing costs for corporations, impacting overall economic activity.

Conclusion

  • Understanding the distinction between nominal and real interest rates, alongside credit spreads, is crucial for comprehending macroeconomic dynamics and the ISLM model's applications.
  • These extensions provide a more realistic framework for analyzing economic conditions and the impact of monetary policy.