# Interest Rate Parity

Interest Rate Parity (IRP) is a theory stating that the interest rate differential between two countries is equal to the forward exchange rate premium or discount.

In other words, the interest rate difference between the two countries should be offset by a forward exchange rate premium or discount, so that investors can get the same return on investment no matter which country they invest in.

## What is interest rate parity?

Interest rate parity (IRP) is a basic concept in international finance that establishes the relationship between interest rates, foreign exchange rates and arbitrage potential.

According to theory, the interest rate difference between two countries should be equal to the expected change in the exchange rate between the two countries.

This means that when interest rate parity is established, there should be no arbitrage opportunities in the foreign exchange market.

IRP plays a vital role in determining the forward rate, which is the rate at which one currency can be converted into another currency at a future date.

Forward rates are calculated by adjusting the current spot rate based on the interest rate differential between two currencies.

The principle behind interest rate parity is that investors should be indifferent to investing in two different currencies, given the risks associated with currency fluctuations.

If interest rate parity does not hold, arbitrageurs can take advantage of this difference and earn risk-free profits by borrowing in a currency with a lower interest rate, converting it into a currency with a higher interest rate, and then investing in that currency.

This process will continue until arbitrage opportunities disappear and interest rate parity is re-established.

## Two interest rates are parity

There are two types of interest rate parity:

1. Covered Rate Parity: This occurs when forward contracts are used to hedge foreign exchange risk. According to covered interest rate parity, the forward exchange rate should equal the spot exchange rate multiplied by the ratio of the interest rates on the two currencies.
2. Undisclosed Interest Rate Parity: This version assumes that FX risk is unhedged. It states that the expected change in the exchange rate between two currencies should be equal to the difference in their nominal interest rates.

## Is interest rate parity a load of crap?

IRP is a useful tool for investors trying to compare investment returns in different countries. It can also be used to speculate on the future value of a currency.

However, it is important to note that IRP is only a theory and does not always hold true in practice.

In reality, interest rate parity does not always hold true due to various factors such as transaction costs, political risks, different tax systems, inflation, risk aversion, etc.

However, it remains a key concept in international finance, helping investors and policymakers understand the relationship between interest rates and exchange rates.