Interest Rate Parity

Interest Rate Parity is a financial theory that describes the relationship between interest rates and exchange rates in the context of international financial markets. The theory posits that the difference in interest rates between two countries is equal to the difference between the forward exchange rate and the spot exchange rate, adjusted for risk. This concept is frequently used in foreign exchange (Forex) markets to predict future exchange rates based on current interest rates.

Basic Concept

Interest Rate Parity aims to prevent arbitrage opportunities arising from discrepancies in interest rates between two countries. According to the theory, if a pair of currencies does not fulfill the interest rate parity condition, then it would be possible for traders to borrow money in the country with the lower interest rate, invest in the country with the higher interest rate, and then hedge this investment through the foreign exchange market to earn a risk-free profit. Interest Rate Parity acts as a fundamental equilibrium condition that prevents such arbitrage opportunities.

Types of Interest Rate Parity

  • Covered Interest Rate Parity: This concept applies when an investment is covered or hedged against exchange rate risk through a forward contract. According to the Covered Interest Rate Parity, the forward premium (or discount) should be equal to the interest rate differential between the two countries.
  • Uncovered Interest Rate Parity: In this case, the investment is not hedged against foreign exchange risk. The theory states that the expected appreciation or depreciation of one currency relative to another should be proportional to the interest rate differential between the two countries.


  • Capital Mobility: Free flow of capital across borders.
  • No Transaction Costs: There are no costs associated with converting currencies.
  • Risk Neutrality: Investors are indifferent to risk.
  • Rational Expectations: All players in the market have rational expectations about future events.


  • Foreign Exchange Markets: Traders use interest rate parity to make predictions about future currency movements.
  • International Investment: Helps investors decide where to allocate assets.
  • Economic Policy: Policy-makers can use it to assess the long-term effects of changes in interest rates.
  • Risk Management: Firms may use it to hedge against unfavorable currency movements.

Limitations and Criticisms

  • Real-World Deviations: In reality, transaction costs, capital controls, and risks often result in deviations from interest rate parity.
  • Time-Varying Risk Premia: Investors may not always be risk-neutral, affecting the theory's applicability.
  • Ignores Other Factors: Factors like political stability, fiscal policy, and economic conditions are not considered.

See Also