Quote from jwcapital:
Seems there is a great deal of confusion regarding entering IC's. It is true that when you enter a credit IC, you are buying. Here is why: When I set up a credit IC, the bid/ask are negative numbers. The bid/for example may be -8.00 and the ask may
-7.00. Remember, -8.00 is SMALLER than -7.00. If you hit the ask, you are buying a credit IC. Why are the numbers negative? Accounting principals. A credit to you is negative, for you are taking away money from someone, whereas a debit is a positive number-you are giving money to someone. In any case, when I set up an iron condor with IB's TWS, the bid/ask are negative numbers. You will encounter this with all credit spreads. Conversely, all debit spreads will be positive numbers. This applies only to spreads. If I want to sell a put, for example, the naked put's bid/ask are positive.