lecture 5 (topic 4 international parity relations and forecasting foreign exchane rates Flashcards
International parity relationships
are manifestations of law of one price that must hold to avoid arbitrage opportunities
Law of one price (LOP)
prevails when the same or equivalent things are trading at the same price across different locations or markets, precluding profitable arbitrage opportunities
Arbitrage
the act of simultaneously buying and selling the same or equivalent assets or commodities for the purpose of making certain, guaranteed profits
Interest rate parity
LOP applied to international money market instruments and provides a linkage between interest rates in two different countries
Purchasing power parity
LOP applied to a standard consumption basket and provides a linkage between prices in two differnt countries
International parity relationships help us understand
how exchange rates are determined and how we can forecast exchagne rates
There are two alternative ways of investing your fund
1) invest in the us dollar at the dollar interest rate (rate i$)
2) Invest in a foreign currency a foreign currency denominated security (for example the british pound) at the interest rate ipound and hedge exchange risk by selling the maturity value of the pound investment forward
Deriving interest rate parity (invest in the US dollar at the dollar interest rate )
(1 + i$)
Deriving interest rate parity (invest in a foreign currency a foreign currency denominated security at the interest rate i pound and hedge exchange risk by selling the maturity value of the pound investment forward
Exchange 1$ for a pound amount, that is pund*(1/S) at the prevailing spot exchange rate (S)
Invest the pound amount at the pound interest rate
Sell the maturity value of the pound investment forward in exchange for a predetermined dollar amount –> $((1/S) * (1 + ipound))*F
simply (F/S)(1+ipound)
Deriving interest rate parity formulas equal
(1+i$) = (F/S)(1+ipound)
Future dollar proceeds from investing in these two equivalent investments must be the same –>
(1+i$) = F/S(1+ipound)
or F = S(1+i$/1+iPound)
IRP can also be derived by
constructing an arbitrage portfolio that involves no net investment and no risk
Borrow $S at the dollar interest rate and buy Pound1 at the prevailing spot exchange rate of S
Lend 1 pound at the pound interest rate
Sell the maturity value of the pound investment forward
Since no one should be able to make certain profits by holding this self-financing portfolio, the net cash flow at maturity should be zero in equilibrium
(1+ipound) * F - (1 +i$)S = 0
Covered interest arbitrage
When IRP does not hold, the situation gives rise to covered interest arbitrage opportunities, allowing certain profits to be made without the arbitrageur investing any money out of pocket or bearing any risk
what if
(1 + i$ > F/S(1+ipound) or (1 + i$ < F/S(1+ipound)
Covered interst arbitrage appx
i$ - ipound = F-S/S