1. Key concept: arbitrage
Chapter Six International Parity Relationships & Forecasting Exchange Rates
Chapter Objective:
This chapter examines several key international parity relationships, such as interest rate parity and purchasing power parity.
It help us to get some insight in (1) how the exchange rates are determined and (2)how to forecast the exchange rates.
Key concept: arbitrage

2. Chapter Outline Interest Rate Parity Purchasing Power Parity
The Fisher Effects
Forecasting Exchange Rates

3. Law of one price（一价定律）
Law of one price means the two things that are equal to each other must be selling for the same price.
Suppose Tom have $1 to invest for one year.
invest in the U.S. at iUS. Maturity value = $1 (1 + ius) (suppose ius
①trade one dollars for pound at the spot rate; ②invest in UK at iUK and ③hedge the exchange rate risk by selling the future value of the British investment forward.

4. Arbitrage defined
Since both of these investments have the same risk (suppose: default-free), they must have the same future value—otherwise an arbitrage would exist.
(F/S)(1 + iUK) = (1 + ius)
Arbitrage is the act of simultaneously buying and selling the same or equivalent assets or commodities for the purpose of making certain guaranteed profits.
If IRP failed to hold, an arbitrage would exist. It’s easiest to see this in the form of an example.

5. Covered Interest arbitrage
If IRP did not hold, then it would be possible for an astute trader to make unlimited amounts of money exploiting the arbitrage opportunity.
If (F/S)(1 + iUK) ＞(1 + ius) →invest in the UK
If (F/S)(1 + iUK) ＜(1 + ius) →invest in the US

6. Interest Rate Parity (IRP) Defined
IRP is an arbitrage equilibrium condition that should hold in the absence of barriers to international financial capital flows.

7. Interest Rate Parity Defined
Formally,
(F/S)(1 + i¥) = (1 + ius)
or if you prefer,
IRP is sometimes approximated as

8. Economic meaning of Interest Rate Parity（IRP）
IRP provides a linkage between interest rate in two different countries.
the forward premium (discount) ≈ the difference in interest rates.
When the interest rate of one currency is higher than the other, this currency should be at a forward discount, F＞S
A. If IUS > IUK, dollar forward discount
B. If IUS < IUK, dollar forward premium

9. How long will the arbitrage opportunity last?
The activity of arbitrage will restore IRP
The opportunity of arbitrage can last only a short while
If (F/S)(1 + iUK) ＞(1 + ius)
Borrow in the US → ius↗
Lend in the UK→ iUK↙
Buy the pound spot →S↗
Sell the pound forward →F↙
Refer to exhibit 6.3
money market adjustment
foreign exchange market adjustment)

10. IRP and Hedging Currency Risk
You are a U.S. importer of British woolens and have just ordered next year’s inventory. Payment of £100M is due in one year.
Spot exchange rate
S($/£) =
$1.25/£
360-day forward rate
F360($/£)
$1.20/£
U.S. discount rate i$
7.10%
British discount rate i£
11.56%
IRP implies that there are two ways that you fix the cash outflow
a) Put yourself in a position that delivers £100M in one year—a long forward contract on the pound. You will pay (£100M)(1.2/£) = $120M
b) Form a forward market hedge as shown below. 4

11. IRP and a Forward Market Hedge
To form a forward market hedge:
Borrow $ million in the U.S. (in one year you will owe $120 million).
Translate $ million into pounds at the spot rate S($/£) = $1.25/£ to receive £89.64 million.
Invest £89.64 million in the UK at i£ = 11.56% for one year.
In one year your investment will have grown to £100 million—exactly enough to pay your supplier. 4

12. Forward Market Hedge
Where do the numbers come from? We owe our supplier £100 million in one year—so we know that we need to have an investment with a future value of £100 million. Since i£ = 11.56% we need to invest £89.64 million at the start of the year.
How many dollars will it take to acquire £89.64 million at the start of the year if S($/£) = $1.25/£? 4

13. Interest rate parity and exchange rate determination
IRP implies that in the short run, the exchange rate depends on (a) the relative interest rare differential between two countries. (b) forward exchange rate.
Forward exchange rate can be viewed as the expected future spot exchange rate conditional on all relevant information currently available.
Expectation plays a key role in exchange determination
Exchange rate changes with the new events.
Refer to page 138

14. Uncovered interest rate parity
It shows that the nominal interest differential equals to the expected change in the exchange rate.
e.g. ius=5%, iuk=8%
→E（e）≈-3%

15. Does interest rate parity really hold?
The IRP relationships has been known among currency traders since late 19th century.
Many empirical tests show that IRP tends to hold quite well.
It applies almost perfectly in the Eurocurrency market.
It applies to many countries that have reduced the restrictions on international capital movement.

16. Reasons for Deviations from IRP
Transactions Costs (see exhibit 6.4 )
The interest rate available to an arbitrageur for borrowing, ib,may exceed the rate he can lend at, il.
There may be bid-ask spreads to overcome, Fb/Sa < F/S
Thus
(Fb/Sa)(1 + i¥l)  (1 + i¥ b)  0
Capital Controls
Governments sometimes restrict import and export of money through taxes or outright bans. (see exhibit 6.5)

17. Purchasing Power Parity
Purchasing Power Parity and Exchange Rate Determination
PPP Deviations and the Real Exchange Rate
Evidence on PPP

18. Purchasing Power Parity and Exchange Rate Determination
PPP is a manifestation of the law of one price applied internationally to a standard commodity baskets
The law of one price P$ =P£* S($/£)
Standard commodity basket (the structure and weight?)
PPP is a way of determinate the equilibrium exchange rate.
S($/£) = P$ / P£
The exchange rate between two currencies should equal the ratio of the countries’ price levels.

19. Purchasing Power Parity and Exchange Rate Determination
PPP is popularized by Gustav Cassel, a Swedish economist in the 1920s.
Some countries; Hyperinflation; currency purchasing power; depreciation
Big mac PPP index (P143)
What is the correct level of exchange rate?

20. Relative PPP Absolute version of PPP
Relative PPP states that the rate of change in an exchange rate is equal to the differences in the rates of inflation.
e = $ - £
If U.S. inflation is 5% and U.K. inflation is 8%, the pound should depreciate by 3%.

21. Evidence on PPP
PPP probably doesn’t hold precisely in the real world for a variety of reasons.
Haircuts cost 10 times as much in the developed world as in the developing world.
Film, on the other hand, is a highly standardized commodity that is actively traded across borders. exhibit 6.7
Substantial barriers to international commodity arbitrage exist (shipping costs, tariffs and quotas) can lead to deviations from PPP.
PPP-determined exchange rates still provide a valuable benchmark. exhibit 6.8

22. The Fisher Effects- another parity relationship
An increase (decrease) in the expected rate of inflation will cause a proportionate increase (decrease) in the interest rate in the country.
For the U.S., the Fisher effect is written as:
i$ = $ + E($)
Where
$ is the equilibrium expected “real” U.S. interest rate
E($) is the expected rate of U.S. inflation
i$ is the equilibrium expected nominal U.S. interest rate

23. International Fisher Effect (LFE)
If the Fisher effect holds in the U.S.
i$ = $ + E($)
and the Fisher effect holds in Japan,
i¥ = ¥ + E(¥)
and if the real rates are the same in each country
$ = ¥
And if the relative PPP holds
E(e) = E($)-E(¥)
then we get the International Fisher Effect
E(e) = i$ - i¥ .

24. International Fisher Effect (LFE)
IFE suggests that the nominal interest differential reflects the expected change in the exchange rate.
What is the difference between IRP and IFM?
Covered Interest Parity
Uncovered Interest Parity

25. International Fisher Effect
If the International Fisher Effect holds,
E(e) = i$ - i¥
and if IRP also holds
then forward expectations parity (FEP) holds.

26. Equilibrium Exchange Rate Relationships
IFE FP
PPP
IRP FE
FPPP
$ - £

27. Forecasting Exchange Rates
Who concern about the change of exchange rates and try to forecast it?
Efficient Markets Approach
Fundamental Approach
Technical Approach
Performance of the Forecasters

28. Efficient Markets Approach
EMH: Financial Markets are efficient if prices reflect all available and relevant information.
If this is so, exchange rates will only change when new information arrives, thus:
St = E[St+1]
and
Ft = E[St+1| It]
Predicting exchange rates using the efficient markets approach is affordable and is hard to beat.

29. Fundamental Approach
uses a variety of formal models of exchange rate determination for forecasting purpose. This involves three steps
step 1: Estimate the structural model to determine the parameter values.
step 2: Estimate future values of the independent variables.
step 3: Use the model to generate the forecasts.
The downside is that fundamental models do not work any better than the forward rate model or the random walk model.

30. Technical Approach
Technical analysis looks for patterns from the past behavior of exchange rates and projects it into the future.
Clearly it is based upon the premise that history repeats itself.
Thus it is at odds with the EMH
Example (P151 exhibit 6.10)
Many traders depend on technical approach for their trading strategies.

31. Performance of the Forecasters
Forecasting is difficult.
As a whole, professional forecasters cannot do a better job of forecasting future exchange rates than the market.
The founder of Forbes Magazine once said:
“You can make more money selling advice than following it.”

32. End Chapter Six