You are completely certain that SPY will not close below $440 tomorrow (Friday).
SPY is $446.26.
You spend every last penny of your life savings, and your brokerage margin, on Friday-expiring...
A. You sink your life savings into the 440 calls. SPY closes at 440.00. You have lost everything.
B. You short the maximum number of naked puts allowed by your broker.
There are two possibilities here.
(1) You make some money, but not very much, because you were only able to sell a few contracts (regardless of Reg T or PM).
(2) Jerome Powell, red-eyed and giggling on live television, says SPY should trade at $420. It gaps to $420 before recovering, triggering a margin call and liquidation of most of your account.
C. You sink your life savings into the 440/445 call spread. SPY closes at 440.00. You have lost everything.
D. You buy the 439/440 call spread. Each costs you around $95. At the end of the day, you know that they will be worth $100.
You can spend every dollar that you have on these spreads, and you know you will have a profit—no chance of loss, and no chance of margin call.
Tons of great answers already in the comments, but perhaps the most concise:
Share this Scrolly Tale with your friends.
A Scrolly Tale is a new way to read Twitter threads with a more visually immersive experience.
Discover more beautiful Scrolly Tales like this.