衍生品代写-BFC2751
时间:2021-08-28
BFC2751 Derivatives 1
Week 3
Chapter 5, Hull
Determination of Forward and Future Prices
Investment vs. Consumption Assets
Investment assets: assets held primarily for
investment purposes.
E.g.: stock, bonds, gold, silver.
Do not have to be held exclusively for investment.
Silver has a number of industrial uses.
Consumption assets: assets held primarily for
consumption purposes.
E.g.: copper, oil, pork bellies.
Use arbitrage arguments to determine the forward
and futures prices of an investment asset but not for
consumption assets.
Short Selling
Short selling involves selling assets you do not own.
Possible for some but not all investment assets.
Your broker borrows the securities from another
client and sells them in the market in the usual way.
Later you must buy the securities back, so they can
be replaced in the account of client.
The investor takes a profit if the stock price has
declined and a loss if it has risen.
Short Selling
You must pay dividends and other benefits the owner
of the securities should receive on the shares.
Margin account is kept with the broker to guarantee
that you do not walk away from your obligations.
Short Selling Example
Investor sells short 100 shares of Commonwealth
Bank at $100 each in March 2016.
Total value: 100 * 100 = $10,000 (receive).
In April, stock pays a dividend of $2 per share.
Total dividend cost: 2*100 = $200 (pay).
In May, investor closes the position by buying back
the shares on the market at $110 each.
Total buy back cost: 110 * 100 = $11,000 (pay).
Profit/loss = $10,000 - $200 - $11,000 = - $1,200.
Assumption and Notation
Assumption market participants:
subject to no transaction costs when they trade.
subject to same tax rate on all net trading profits.
can borrow money at the same risk-free rate of interest
as they can lend money.
take advantage of arbitrage opportunities as they
occur.
S0: Spot price today.
F0: Futures or forward price today.
T: Time to maturity.
r: Risk-free interest rate.
Arbitrage Opportunity
Consider a long forward contract to purchase a non-
dividend-paying stock in 3 months.
Current stock price is $40.
3-months risk-free rate is 5% per annum.
Is there an arbitrage opportunity
Arbitrage Opportunity
Suppose forward price is relative high at $43.
Today:
Borrow $40 @ 5%.
Buy one share.
Short one forward to sell one share at $43 in 3 months.
In 3 months:
Sell the stock at $43.
Repay the loan: 40*e(0.05*3/12) = $40.50.
Profit = 43 - 40.50 = $2.5.
This arbitrage works when F > $40.50.
Arbitrage Opportunity
Suppose forward price is relative low at $39.
Today:
Short one share to realize $40.
Invest $40 @ 5% for 3 months.
Long one forward to buy one share at $39 in 3 months.
In 3 months:
Buy the stock at $39, and close the short position.
Receive from investment: 40*e(0.05*3/12) = $40.50.
Profit = 40.5 - 39 = $1.5.
This arbitrage works when F < $40.50.
There is no arbitrage only when F = $40.50.
Forward Pricing
If the spot price is S0 and the forward price for a
contract deliverable in T years is F0, r is the risk-free
interest rate.
To avoid arbitrage, F0 should be equal to:
F0 = S0erT
This equation relates the forward price and the spot
price for any investment asset that provides no
income and has no storage costs.
E.g., non-dividend-paying stocks, zero-coupon bond.
In our examples, S0 = 40, T = 3/12, and r = 0.05.
F0 =S0erT = 40*e(0.05*3/12) = $40.5.
Forward Pricing: Known Income
Consider a forward contract on an investment asset
that will provide a perfectly predictable cash income to
the holder.
E.g., stock paying known dividends and coupon-
bearing bonds.
F0 = (S0 – I)erT
where I is the present value of the income during life
of forward contract.
Forward Pricing: Known Income
Consider a long forward contract to purchase a coupon-
bearing bond whose current price is $900.
The forward contract matures in 9 months.
A coupon payment of $40 (i.e., income) is expected after
4 months.
4- and 9-month rates (continuously compounded) are 3%
and 4% per annum.
Forward Pricing: Known Income
F=$910: use the income to pay part of the borrowing in 4
month. Take away the PV(I) from the $900 borrowing today.
F=$870: use part of the investment to pay the income of the
shorted asset in 4 month. Take away the PV(I) from the $900
investment today.
Forward Pricing: Known Yield
Consider the situation where the asset underlying a
forward contract provides a known yield rather than a
known cash income.
F0 = S0 e(r–q)T
where q is the average yield during the life of the
contract (expressed with continuous compounding).
Forward Pricing: Known Yield
Stock price is $25 today.
6-month forward contact.