Credit and Debit Spreads

• • A bull call spread is purchasing a call option, and simultaneously selling another call option (on the same underlying asset) with the same expiration date but a higher strike price. Since this is a debit spread, the maximum loss is restricted to the net premium paid for the position, while the maximum profit is equal to the difference in the strike prices of the calls less the net premium paid to put on the position.
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  • A bear call spread is selling a call option, and simultaneously purchasing another call option with the same expiration date but at a higher strike price. Since this is a credit spread, the maximum gain is restricted to the net premium received for the position, while the maximum loss is equal to the difference in the strike prices of the calls less the net premium received.
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  • A bull put spread is writing a put option, and simultaneously purchasing another put option with the same expiration date but a lower strike price. Since this is a credit spread, the maximum gain is restricted to the net premium received for the position, while the maximum loss is equal to the difference in the strike prices of the puts less the net premium received.
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  • A bear put spread is purchasing a put option, and simultaneously selling another put option with the same expiration date but a lower strike price. Since this is a debit spread, the maximum loss is restricted to the net premium paid for the position, while the maximum profit is equal to the difference in the strike prices of the puts less the net premium paid to put on the position.
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  The table below summarizes the basic features of these four spreads. Commissions are excluded for simplicity.

  Spread	Strategy	Strike Prices	Debit / Credit	Max. Gain	Max. Loss	Break-Even
  Bull Call	Buy Call C1 Write Call C2	Strike price of C2 > C1	Debit	(C2 − C1) − Premium paid	Premium paid	C1 + Premium
  Bear Call	Write Call C1 Buy Call C2	Strike price of C2 > C1	Credit	Premium received	(C2 − C1) − Premium received	C1 + Premium
  Bull Put	Write Put P1 Buy Put P2	Strike price of P1 > P2	Credit	Premium received	(P1 − P2) − Premium received	P1 − Premium
  Bear Put	Buy Put P1 Write Put P2	Strike price of P1 > P2	Debit	(P1 − P2) − Premium paid	Premium paid	P1 − Premium

  Credit and Debit Spreads

  Vertical spreads are used for two main reasons:

  1.   For debit spreads, to reduce the premium amount payable.

  2.   For credit spreads, to lower the option position’s risk.

  交易标价的附注：
  
  

  • 如果你买一个价差而且欠钱(debit spread)，则输入正数的限价单。
    如果你买一个价差且收到现金(a credit spread)，你必须输入一个负值的限价单。
  • 相反，如果你卖出一个价差且收到现金，则输入一个正的限价单。
    如果卖出一个差价且欠钱，则必须输入一个负值的限价单。

  例如，一个四月的20块的XYZ 买权，显示买价6.60和卖价6.70，另一个四月的30块的XYZ买权显示0.15对0.20.
  如果你用下面的脚买一个“debit”的买权垂直价差/套利：
  Buy 1 OPT APR02 20.0 CALL (6.70),
  Sell 1 OPT APR02 30.0 CALL (0.15)
  对这个交易，你将支付6.55（一个debit的交易），正价格的spread限价单。
  
  当你翻转上面的脚，用下面的脚来买一个credit买权垂直套利/价差：
  Sell 1 OPT APR02 20.0 CALL (6.60)
  Buy 1 OPT APR02 30.0 CALL (0.20)