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In options trading, a box spread is a combination of positions that has a certain (''i.e.'' riskless) payoff, considered to be simply "delta neutral interest rate position". For example, a bull spread constructed from calls (''e.g.'' long a 50 call, short a 60 call) combined with a bear spread constructed from puts (''e.g.'' long a 60 put, short a 50 put), has a constant payoff of the difference in exercise prices (e.g. 10). Under the no-arbitrage assumption the net premium paid out to acquire this position should be equal to the present value of the payoff. They are often called "alligator spreads" because the commissions eat up all your profit due to the large number of trades required for most box spreads. The box-spread usually combines two pairs of options; and its name derives from the fact that the prices for these options form a rectangular box in two columns of a quotation. Note that box spreads also form a strategy in futures trading - see below. ==Background== 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 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Box spread」の詳細全文を読む スポンサード リンク
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