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  • Some fundamental questions of international financialmanagers are:

    - What are the determinants of exchange rates?- Are changes in exchange rates predictable?

    The economic theories that link exchange rates, price levels, and interest rates together are called international parity conditions.

    These international parity conditions form the core of the financial theory that is unique to international finance.


    Prof. Dr. Pornchai Chunhachinda

    International Parity Conditions

    If the identical product or service can be sold in two different markets, and no restrictions exist on the sale or transportation costs of moving the product between markets, the products price should be the same in both markets.

    This is called the law of one price.


    Prof. Dr. Pornchai Chunhachinda

    1. The Law of One Price

    A primary principle of competitive markets is that prices will equalize across markets if frictions (transportation costs) do not exist. Comparing prices then, would require only a conversion

    from one currency to the other:

    P$ x S = P

    Where the product price in US dollars is (P$), and the price in Baht is (P) the spot exchange rate is (S)(Direct Quote).


    Prof. Dr. Pornchai Chunhachinda

    If the law of one price were true for all goods and services, the purchasing power parity (PPP) states that exchange rate could be found from any set of prices.


    Prof. Dr. Pornchai Chunhachinda

    2. Absolute Purchasing Power Parity

  • By comparing the prices of identical set of products denominated in different currencies, we could determine the real or PPP exchange rate that should exist if markets were efficient.

    PI$ x S = PI

    Where the prices of identical set of products in US dollars is (PI$), the prices of identical set of products in Baht is (PI) and the spot exchange rate is (S) (Direct Quote). This is the absolute version of the PPP theory.


    Prof. Dr. Pornchai Chunhachinda

    If the assumptions of the absolute version of the PPP theory are relaxed a bit more, we observe what is termed relative purchasing power parity (RPPP).

    RPPP holds that the relative change in prices between two countries over a period of time determines the change in the exchange rate over that period.


    Prof. Dr. Pornchai Chunhachinda

    3. Relative Purchasing Power Parity

    More specifically, if the spot exchange rate between two countries starts in equilibrium, any change in the differential rate of inflation between them tends to be offset over the long run by an equal but opposite change in the spot exchange rate.

    S1 = 1+IS0 1+I$

    S1, S0 = Spot Exchange Rate (/ $) at time 1, 0I = Inflation Rate of ThailandI$ = Inflation Rate of U.S.A.


    Prof. Dr. Pornchai Chunhachinda


    Prof. Dr. Pornchai Chunhachinda

    Purchasing Power Parity (PPP)Percent change in the spot exchangerate for foreign currency

    Percent difference inexpected rates of inflation

    (foreign relative tohome country)





    -1-3 -1-4 -2 2 41 3 5





    -6 6


  • Empirical testing of PPP and the law of one price has been done, but has not proved PPP to be accurate in predicting future exchange rates.

    Two general conclusions can be made from these tests:

    - PPP holds up well over the very long run but poorly for shorter time periods.

    - The theory holds better for countries with relatively high rates of inflation and underdeveloped capital markets.


    Prof. Dr. Pornchai Chunhachinda

    Empirical Test of PPP The Fisher Effect states that nominal interest rates in

    each country are equal to the required real rate of return plus compensation for expected inflation

    This equation reduces to (in approximate form):i = (1+r)(1+ )-1

    = r + + r= r +

    Where i = nominal interest rater = real interest rate = expected inflation.


    Prof. Dr. Pornchai Chunhachinda

    4. The Fisher Effect

    Currencies with high rates of inflation should bear higher interest rates than currencies with lower rates of inflation.

    1+ d = 1+id1+ f 1+if

    Empirical Tests of Fisher Effect1. For short-term, the Fisher Effect holds.

    2. For long-term, the Fisher Effect affected byincreased financial risks.

    3. For private securities, the comparison areinfluenced by unequal creditworthiness of the issuers.


    Prof. Dr. Pornchai Chunhachinda

    The relationship between the percentage change in the spot exchange rate over time and the differential between comparable interest rates in different national capital markets is known as the InternationalFisher Effect.

    Fisher-open, as it is termed, states that the spot exchange rate should change in an equal amount but in the opposite direction to the difference in interest rates between two countries.


    Prof. Dr. Pornchai Chunhachinda

    5. The International Fisher Effect

  • More formally:S0 S1

    Where i$ and i are the respective national interest rates and S is the spot exchange rate using direct quotes ( /$).

    Justification for the international Fisher effect is that investors must be rewarded or penalized to offset the expected change in exchange rates.


    Prof. Dr. Pornchai Chunhachinda

    S1 x 100 = i$ - i

    Currencies with lower interest rates are expected toappreciate relative to currencies with higher interestrates.

    S1 = S0 1+i 1+i$

    Empirical Tests of International Fisher Effect1. Lend some support to the International FisherEffect.

    2. Indicate the long-run tendency for interestdifferentials to offset exchange rate changes.


    Prof. Dr. Pornchai Chunhachinda

    The theory of Interest Rate Parity (IRP) provides the linkage between the foreign exchange markets andthe international money markets.

    The theory states: The difference in the national interest rates for securities of similar risk and maturity should be equal to, but opposite in sign to, the forward rate discount or premium for the foreign currency, except for transaction costs.


    Prof. Dr. Pornchai Chunhachinda

    6. Interest Rate Parity The forward rate is calculated for any specific

    maturity by adjusting the current spot exchange rate by the ratio of eurocurrency interest rates of the same maturity for the two subject currencies.

    F = 1+id S 1+if


    Prof. Dr. Pornchai Chunhachinda

  • For example, the 90-day forward rate for the Swiss franc/US dollar exchange rate (FSF/$90) is found by multiplying the current spot rate (SSF/$) by the ratio of the 90-day euro-Swiss franc deposit rate (iSF) over the 90-day eurodollar deposit rate (i$).

    F = 1+id S 1+if


    Prof. Dr. Pornchai Chunhachinda


    Prof. Dr. Pornchai Chunhachinda

    Interest Rate Parity (IRP)

    90 days

    Dollar money market

    Swiss franc money market

    $1,000,000 $1,020,000$1,019,993*

    S = SF 1.4800/$

    SF 1,480,000 SF 1,494,800

    F90 = SF 1.4655/$

    x 1.01

    x 1.02Start End

    i $ = 8.00 % per annum(2.00 % per 90 days)

    i SF = 4.00 % per annum(1.00 % per 90 days)

    Note that the Swiss franc investment yields $1,019,993, $7 less on a $1 million investment.

    The forward premium or discount is the percentage difference between the spot and forward exchange rate, stated in annual percentage terms.

    f SF = Spot Forward

    This is the case when currency SF/$ is used.


    Prof. Dr. Pornchai Chunhachinda

    Forward360days 100xx


    Prof. Dr. Pornchai Chunhachinda

    Currency Yield Curves & The Forward Premium

    Euro Swiss francyield curve


    Days Forward60 12030 90 150 180

    Eurodollaryield curve

    Forward premium is thepercentage difference of 3.96%

    1.0 %

    3.0 %

    4.0 %

    5.0 %

    6.0 %

    2.0 %

    7.0 %

    8.0 %

    9.0 %

    10.0 %

  • The spot and forward exchange rates are not, however, constantly in the state of equilibrium described by interest rate parity.

    When the market is not in equilibrium, thepotential for risk-less or arbitrage profit exists.

    The arbitrager will exploit the imbalance by investing in whichever currency offers the higher return on a covered basis.

    This is known as covered interest arbitrage (CIA).21

    Prof. Dr. Pornchai Chunhachinda

    7. Covered Interest Arbitrage


    Prof. Dr. Pornchai Chunhachinda

    Covered Interest Arbitrage (CIA)

    180 days

    Dollar money market

    Yen money market

    $1,000,000 $1,040,000$1,044,638

    S = 106.00/$

    106,000,000 108,120,000

    F180 = 103.50/$

    x 1.02

    x 1.04Start End

    Eurodollar rate = 8.00 % per annum

    Euroyen rate = 4.00 % per annum


    The following exhibit illustrates the conditions necessary for equilibrium between interest rates and exchange rates.

    The disequilibrium situation, denoted by pointU, is located off the interest rate parity line.

    However, the situation represented by point U is unstable because all investors have an incentive to execute the same covered interest arbitrage, which is virtually risk-free.


    Prof. Dr. Pornchai Chunhachinda


    Prof. Dr. Pornchai Chunhachinda

    Interest Rates Parity (IRP) and Equilibrium






    -3 -1-4 -2 2 41 3 5





    -6 6

    XPercent difference between foreign ()and domestic ($) interest rates

    Percentage premium onfo


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