Box spread (options)

An arbitrage operation may be represented as a sequence which begins with zero balance in an account, initiates transactions at time t = 0, and unwinds transactions at time t = T so that all that remains at the end is a balance whose value B will be known for certain at the beginning of the sequence. If there were no transaction costs then a non-zero value for B would allow an arbitrageur to profit by following the sequence either as it stands if the present value of B is positive, or with all transactions reversed if the present value of B is negative. However, market forces tend to close any arbitrage windows which might open; hence the present value of B is usually insufficiently different from zero for transaction costs to be covered. This is considered typically to be a "Market Maker/ Floor trader" strategy only, due to extreme commission costs of the multiple-leg spread. If the box is for example 20 dollars as per lower example getting short the box anything under 20 is profit and long anything over, has hedged all risk .

A present value of zero for B leads to a parity relation. Two well-known parity relations are:-

• Spot futures parity. The current price of a stock equals the current price of a futures contract discounted by the time remaining until settlement:

• Put call parity. A long European call c together with a short European put p at the same strike price K is equivalent to borrowing ${\displaystyle Ke^{-rT}}$ and buying the stock at price S. In other words, we can combine options with cash to construct a synthetic stock:

Note that directly exploiting deviations from either of these two parity relations involves purchasing or selling the underlying stock.

Now consider the put/call parity equation at two different strike prices ${\displaystyle K_{1}}$ and ${\displaystyle K_{2}}$. The stock price S will disappear if we subtract one equation from the other, thus enabling one to exploit a violation of put/call parity without the need to invest in the underlying stock. The subtraction done one way corresponds to a long-box spread; done the other way it yields a short box-spread. The pay-off for the long box-spread will be the difference between the two strike prices, and the profit will be the amount by which the discounted payoff exceeds the net premium. For parity, the profit should be zero. Otherwise, there is a certain profit to be had by creating either a long box-spread if the profit is positive or a short box-spread if the profit is negative. [Normally, the discounted payoff would differ little from the net premium, and any nominal profit would be consumed by transaction costs.]

The long box-spread comprises four options, on the same underlying asset with the same terminal date. They can be paired in two ways as shown in the following table (assume strike-prices ${\displaystyle K_{1}}$ < ${\displaystyle K_{2}}$):

	Long bull call-spread	Long bear put-spread
Long synthetic stock	Buy call at ${\displaystyle K_{1}}$	Sell put at ${\displaystyle K_{1}}$
Short synthetic stock	Sell call at ${\displaystyle K_{2}}$	Buy put at ${\displaystyle K_{2}}$

Reading the table horizontally and vertically, we obtain two views of a long box-spread.

• A long box-spread can be viewed as a long synthetic stock at a price ${\displaystyle K_{1}}$ plus a short synthetic stock at a higher price ${\displaystyle K_{2}}$.
• A long box-spread can be viewed as a long bull call spread at one pair of strike prices, ${\displaystyle K_{1}}$ and ${\displaystyle K_{2}}$, plus a long bear put spread at the same pair of strike prices.

We can obtain a third view of the long box-spread by reading the table diagonally. A long box-spread can be viewed as a long strangle at one pair of strike prices, ${\displaystyle K_{1}}$ and ${\displaystyle K_{2}}$, plus a short strangle at the same pair of strike prices.

• The long strangle contains the two long (buy) options.
• The short strangle contains the two short (sell) options.

A short box-spread can be treated similarly.

As an example, consider a three-month option on a stock whose current price is $100. If the interest rate is 8% per annum and the volatility is 30% per annum, then the prices for the options might be:

	Call	Put
${\displaystyle K_{1}=90}$	$13.10	$ 1.65
${\displaystyle K_{2}=110}$	$3.05	$10.90

The initial investment for a long box-spread would be $19.30. The following table displays the payoffs of the 4 options for the three ranges of values for the terminal stock price ${\displaystyle S_{T}}$:

${\displaystyle S_{T}<K_{1}}$		${\displaystyle K_{1}<S_{T}<K_{2}}$		${\displaystyle K_{2}<S_{T}}$
${\displaystyle 0}$	${\displaystyle S_{T}-90}$	${\displaystyle S_{T}-90}$	${\displaystyle 0}$	${\displaystyle S_{T}-90}$	${\displaystyle 0}$
${\displaystyle 0}$	${\displaystyle 110-S_{T}}$	${\displaystyle 0}$	${\displaystyle 110-S_{T}}$	${\displaystyle 110-S_{T}}$	${\displaystyle 0}$

The terminal payoff has a value of $20 independent of the terminal value of the share price. The discounted value of the payoff is $19.60. Hence there is a nominal profit of 40 cents to be had by investing in the long box-spread.

To what extent are the various instruments introduced above traded on exchanges? Chaput and Ederington, surveyed Chicago Mercantile Exchange's market for options on Eurodollar futures. For the year 1999–2000 they found that some 25% of the trading volume was in outright options, 25% in straddles and vertical spreads (call-spreads and put-spreads), and about 5% in strangles. Guts constituted only about 0.1%, and box-spreads even less (about 0.01%). [Ratio spreads took more than 15%, and about a dozen other instruments took the remaining 30%. This is considered typically to be a "Market Maker/Floor trader" strategy only, due to extreme commission costs of the multiple leg spread. If the box is for example 20 dollars as per lower example getting short the box anything under 20 is profit and long anything over, has hedged all risk. In 2019, the online-only brokerage Robinhood changed its risk management policy due to a box spread suffering assignment risk from Reddit user 1R0NYMAN.[2]

• Uri, Benzion; Shmuel, Danan; Joseph, Yagil (Spring 2005). "Box Spread Strategies and Arbitrage Opportunities". The Journal of Derivatives. 12 (3): 47–62. doi:10.3905/jod.2005.479379.
• Bharadwaj, Anu; Wiggins, James B. (2001). "Box spread and put-call parity tests for the S&P 500 index LEAPS market". The Journal of Derivatives. 8 (4): 62–71. doi:10.3905/jod.2001.319163. The box-spread reveals an arbitrage profit insufficient to cover transaction costs.
• Billingsley, R.S.; Chance, Don M. (1987). "Options market efficiency and the box spread strategy". Financial Review. 20 (4): 287–301. doi:10.1111/j.1540-6288.1985.tb00309.x.
• Chance, Don M. (2001). An Introduction to Derivatives (5th ed.). Thomson.
• Chaput, J. Scott; Ederington, Louis H. (January 2002). "Option spread and combination trading". SSRN 296036.
• Hemler, Michael L.; Miller, Jr., Thomas W. (1997). "Box spread arbitrage profits following the 1987 market crash: real or illusory?". Journal of Financial and Quantitative Analysis. 32 (1): 71–90. doi:10.2307/2331317. JSTOR 2331317.. Post-market simulations with box-spreads on the S&P 500 Index show that market ineffiency increased after the 1987 crash.
• Hull, John C. (2002). Fundamentals of Futures and Options Markets (4th ed.). Prentice-Hall.
• Ronn, Edud; Gerbarg Ronn, Aimee (1989). "The Box spread arbitrage conditions: theory, tests, and investment strategies". Review of Financial Studies. 2 (1): 91–108. doi:10.1093/rfs/2.1.91. The box-spread is used to test for arbitrage opportunities on Chicago Board Options Exchange data.