The Pricing of Forward and Futures

Read Hull Chapter 5

Outline

  • Short selling
  • Arbitrage
  • Asset earns income
  • Index futures
  • Currency forwards and futures
  • Storage costs
  • The cost of carry
  • Arbitrage examples

Short Sellling

  • Consumption and Investment Assets
    • People hold investment assets purely for investment purposes such as gold and silver
    • People hold consumption assets primarily to consume such as copper and oil
  • Short Selling
    • Investor sells securities he or she does not own
    • Investor or broker borrows the securities from another client and sells them in the market in the usual way
    • At some stage, investor must buy the securities so he or she replaces in the client's account
    • He or she must pay dividends and other benefits to the owner of the securities
      • Investor doesn't own the securities
      • Investor may pay a small fee for borrowing the securities
    • Example
      • You short 100 shares when the price is $100 and close out the short position three months later when the price is $90
      • During the three months, a dividend of $3 per share is paid
      • What is your profit?
      • What would be your loss if you had bought 100 shares?
        • Short - You sell a 100 shares for $100 and receive $10,000
        • Dividend - Tricky
          • You sold the stock and buyer gets the dividend
          • You deduct the $3 dividend, or $300
          • Buy 100 shares for $90, or -$9,000
          • Profit from shorting
            • Profit = $10,000 - $300 – 9,000 = $700
          • Loss if purchased long
            • Profit = $9,000 + $300 - $10,000 =-$700

Arbitrage

  • Notation to value futures and forward contracts
S0 Spot price toda while subscript 0 means time = 0
F0 Futures or forward price today
T Time until delivery date at time T
r Risk-free interest rate until maturity T
  • An arbitrage example
    • The spot price of a non-dividend-paying stock is $40
    • The 3-month forward price is $43
    • The 3-month US$ interest rate is 5% per annum
    • Does an arbitrage opportunity exist?
      • Theoretical price, F0=S0 ert=$40 e0.05 (3/12)=$40.50
      • Arbitrage opportunity if F does not equal F0
      • Since Factual $43 > theoretical F0 40.50
        • Buy low and sell high
        • You short the forward contract
        • Borrow money at 5% from the bank
        • Buy the stock at $40 while interest is 0.50
      • After three months,
        • your receive $43
        • repay bank loan with interest of $40.50
        • profit equals $43 - $40.50 = $2.50
  • Another example
    • The spot price of nondividend-paying stock is $40
    • The 3-month forward price is US$39
    • The 1-year US$ interest rate is 5% per annum
    • Does an arbitrage opportunity exist?
      • Theoretical price, F0=S0 ert=$40 e0.05 (3/12)=$40.50
      • Arbitrage opportunity if F does not equal F0
      • Since Factual $39 < theoretical F0
        • Buy low and sell high
        • You short the asset for $40
        • Go long on forward contract
        • You deposit money at a bank and earn 5%
      • At maturity
        • You receive $40.50 from the bank
        • Buy stock at $39 and earn $1.50 in profit.
        • Then you return the borrowed shares and close short
  • Non-contiinuous compounding interest
    • The spot price of an investment asset equals S0
    • The futures price for a contract deliverable in T years is F0
    • The risk-free interest rate, r, that is non-continuous
    • Then F0 = S0(1+r)T
    • In the previous example
      • S0 = 40, T = 0.25, and r = 0.05 so that F0 = 40(1.05)0.25 = 40.5
  • If Short Sales Are Not Possible
    • Formula still works for an investment asset
    • Investors who hold the asset will sell it and buy forward contracts when the forward price is too low

Asset Earns Income

  • Assets earns a known dollar income
    • You do not own the asset in the forward contract
    • You do not receive that income, so deduct income from equation
    • After paying income, it lowers the value of the asset
    • Dividend lowers the spot price of stock after a company pays it.
      • F0 = ( S0 – I ) e rT
      • where I is the present value of the income during life of forward contract
  • An investment asset earns a known yield
    • The average yield during the life of the contract equals q
      • q is continuous compounding
      • q could be a stock earning a percent dividend
      • Remove impact of income since holder does not earn it
      • F0 = S0 e( r–q )T
  • Valuing a Forward Contract
    • A forward contract is worth zero except for bid-offer spread effects when it is first negotiated
    • Delivery price, K, price specified in the forward contract
    • F0 – market value of forward
    • Must equal each other at Time 0, otherwise, one party pays the other party money.
    • Later, forward contract could have a positive or negative value
  • Valuing a Forward Contract
    • The market value of the forward contract can change over time
    • The value of a long forward contract
      • PV = (F0 − K)e−rT
      • You can buy at K and sell at F0
      • e-rT is to discount a future cash flow to today's value
    • The value of a short forward contract
      • PV = (K – F0 )e–rT
      • You can buy at F0 and sell at K
  • Forward vs Futures Prices
    • When the maturity and asset price are the same, forward and futures prices are usually assumed to be equal.
    • Eurodollar futures are an exception
    • Eurodollar futures uses an equation to calculate value
  • Forward vs Futures Prices
    • When interest rates are uncertain they are, in theory, slightly different:
    • A strong positive correlation between interest rates and the asset price implies the futures price is slightly higher than the forward price
      • If asset price increases, then interest rates increase too.
      • Thus, the spot rate increases.
      • The value of the contract increases because holder buys at the K price and sells to the spot rate
      • Balance in margin account increases, so holder can withdraw money and earn the higher interest
      • Future have higher value than forward
    • A strong negative correlation implies the reverse using similar logic

Stock Index

  • Treat as an investment asset paying a dividend yield
    • The relationship between futures price and spot price
      • F0 = S0 e(r–q )T
      • where q is the dividend yield on the portfolio represented by the index during life of contract
    • For the formula to be true, the index should represent the investment asset
      • Changes in the index must correspond to changes in the value of a tradable portfolio
      • The Nikkei index comprised of 225 Japanese stock is denominated in Japanese yen
      • The futures for Nikkei index pays out in U.S. dollars
  • Index Arbitrage
    • When Factual > S0e(r-q)T an arbitrageur:
      • Borrows from the bank
      • Buys the stocks underlying the index
      • Sells futures
      • At maturity
        • The arbitrageur gives the holder the stocks
        • Takes the money,
        • Repays the bank loan
    • When Factual < S0e(r-q)T an arbitrageur:
      • Shorts (or sells) the stocks
      • Buys futures
      • Invest funds in a bank to earn interest.
      • On maturity
        • The arbitrageur cashes out investment
        • Takes the stocks
        • Gives stocks to the source where he/she received them, and earns a profit.
  • Index arbitrage involves simultaneous trades in futures and many different stocks
    • Very often a computer is used to generate the trades
    • Occasionally simultaneous trades are not possible and the theoretical no-arbitrage relationship between F0 and S0 does not hold

Currency Futures and Forwards

  • A foreign currency is analogous to a security providing a yield
  • Exchange rate = home currency / foreign currency
  • The yield is the foreign risk-free interest rate
  • It follows that if rf is the foreign risk-free interest rate, then r is the interest rate for the home currency

pricing currency forward

  • Continuous

pricing currency forward

  • Discrete from international finance

pricing currency forward

  • The diagram below shows a box diagram.
  • Investor starts with $1.
    • He or she can invest in the U.S. to earn interest r
    • At the end of the investment, investor has erT
    • Investor can invest in a foreign country
    • Investor converts $1 to foreign currency by dividing by the spot rate, S0
    • Investor earns foreign interest erfT / S0
    • Investor uses currency forward to return money home, which equals F0 erft / S0

international arbitrage

  • Since investor can invest in domestic or foreign country, arbitrage causes both investment paths to equal
    • The pricing of a currency forward is shown below
    • Assume the investor believes he or she has the same risk in the foreign country

pricing currency forward

Storage Costs

  • Consumption Assets
  • Storage is negative income, the opposite of income
    • F0 ≤ S0 e( r+u )T
    • where u is the storage cost per unit time as a percent of the asset value.
  • Alternatively, F0 ≤ (S0+U )erT where U is the present value of the storage costs.

The Cost of Carry

  • Cost of carry - includes insurance, storage and interest on the invested funds
    • For futures markets, it equals the difference between the yield on a cash instrument and the cost of the funds necessary to buy the instrument
  • Nondividend paying stock
    • Cost of carry is only r
    • No income and no storage costs
  • Dividend paying stock
    • Cost of carry is r – q
    • Earns income but no storage costs
  • Consumption asset commodity provides income at q
    • Requires storage costs
    • Must pay interest to borrow from a bank
    • The cost of carry, c, is the storage cost plus the interest costs less the income earned
    • c = r + u
    • Could include income c = r + u – q
    • Contango – forward price is greater than spot price
    • For an investment asset F0 = S0ecT
  • Consumption assets can have a lower futures price than spot price
    • Backwardation
    • For a consumption asset F0 ≤ S0ecT
  • The convenience yield on the consumption asset, y, is defined
    • F0 = S0 e(c–y )T
    • Same equation F0 ≤ S0ecT
    • Implies the risk-free interest rate is negative
    • Add a fudge factor, so risk-free interest rate is positive
    • Convenience yield – an implied return to the holder because he or she holds inventory
    • Asset has frequent shortages, price spikes, or seasonal effects like a dry spell
    • Petroleum and agricultural commodities
    • Holder does not use the asset for income purposes
  • Expected Future Spot Prices
    • Suppose k is the expected return required by investors in an asset
    • We can invest F0e–r T at the risk-free rate and enter into a long futures contract to create a cash inflow of ST at maturity
    • This shows that F0e-rT ekT = E(ST)
    • or F0 = E(ST)e(r-k)T
    • Future price depends on a expected spot price at Time T based on the risk-free interest minus any income earned
No Systematic Risk k = r F0 = E(ST)
Positive Systematic Risk k > r F0 < E(ST)
Negative Systematic Risk k < r F0 > E(ST)
 
  • Positive systematic risk: stock indices
  • Negative systematic risk: gold (at least for some periods)

Arbitage Examples

  • A gold arbitrage opportunity
    • The spot price of gold is US $1,700 per ounce
    • The quoted 1-year futures price of gold is US$1,800
    • The 1-year US$ interest rate is 5% per annum
    • No income or storage costs for gold
    • Does an arbitrage opportunity exists?
      • Use the formula
      • F = S (1+r)T = 1700(1+0.05)1 = 1,785
      • Strategy - treat this as a risk-free investment
        • If I invest $1,700 today, it grows into $1,785 in one year
        • Theoretical (calculated) value of futures contract equals $1,785 but actual value is $1,800.
        • Buy low and sell high
        • Borrow $1,700 today and buy gold
        • Sell futures contract In one year
        • On maturity
          • Sell the gold in the contract
          • Repay loan for $1,785
          • Profit = 1,800 – 1,785 = $15 per ounce
  • Second gold: arbitrage opportunity
    • The spot price of gold is US$1,700
    • The quoted 1-year futures price of gold is US$1,680
    • The 1-year US$ interest rate is 5% per annum
    • No income or storage costs for gold
    • Does an arbitrage opportunity exists?
      • Actual futures price < theoretical futures price
      • Short gold today at spot price $1,700 i.e. sell gold in the future
      • You do not have gold now
      • Invest money at 5%
      • Buy futures contract and agree to buy $1,680
      • On maturity
        • You replace the gold In one year
        • Buy gold at $1,680
        • Close short position
        • Receive $1,785 in interest
        • Profit = $1,785 - $1,680 = $105 per ounce
  • An oil arbitrage opportunity
    • The spot price of oil is US$80
    • The quoted 1-year futures price of oil is US$90
    • The 1-year US$ interest rate is 5% per annum
    • The storage costs of oil are 2% per annum
    • Does an arbitrage opportunity exists?
      • Caculate theoretical price
      • F0 = S0 e(r+u)T = $80 e(0.05+0.02)(1) = $85.80
      • Actual $90 > theoretical $85.80
      • Buy low and sell high
      • Sell the futures for oil
      • Borrow funds to buy the oil
      • On maturity
        • Sell the oil via the futures
        • Repay the bank
        • Pay the storage costs
        • UC has never asked this type of problem
  • An oil arbitrage opportunity
    • The spot price of oil is US$80
    • The quoted 1-year futures price of oil is US$75
    • The 1-year US$ interest rate is 5% per annum
    • The storage costs of oil are 2% per annum
    • Does an arbitrage opportunity exists?
      • Caculate theoretical price F0 = S0 e(r+u)T = $80 e(0.05+0.02)(1) = $85.80
      • Actual $75 < theoretical $85.80
      • Buy low and sell high
      • Buy the futures for oil
      • Short the oil
      • Invest the funds to earn interest
      • On maturity
        • Buy the oil via the futures
        • Repay the bank
        • Collect the storage costs and close the short
        • UC has never asked this type of problem

 

 

 

 

 

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