Quote from Put_Master:
Perhaps oldnemesis will explain for us, how blueplayer sold 645 spread contracts of FB at $25/23,.... with just $100,000???
Can anyone explain it?
I'd also love to know, how he sold 400 naked puts at $25 with that same $100,000, using 40% margin.
Even if you raise the margin to the max, how do you get to use that much leverage?
Hello Put_Master, the math for the vertical spread is simple arithmetic. The spread needs $2 of margin per contract and you are selling them at $0.45, so from your own money you only need $1.55. Therefore:
100000/(1.55*100)=645.16
I just rounded to 645

I hope that that is clear now. You can use the proceeds of the sale to complete the margin req (as opposed to the case when you write naked puts).
For the naked puts in your case I used the margin requirements from Interactive Brokers which for this example was only 10% of strike + premium. Therefore:
100000/(2.5*100) = 400 (you can't use the premium collected to complete the margin).
With regards to the 40% number that you keep mentioning that is the point where you are confused, and in fact I can tell that you have never written a naked put in a Reg T. margin account (which is not really a bad thing at all). The margin requirements for naked puts are very different to the ones for normal equities so you when you talk about that 40% margin you are using the wrong number.
In fact just to bury this subject once and for all, I'm going to use the margin req from the official Margin Handbook from Schwab as of 8/01/12 to compute the numbers again.
On page 14 of the document you can see that the Margin requirement for this naked sell is:
Greater of:
1. 25% underlying value â out of the money amount + premium
2. 10% strike price + premium
3. Lesser of $100 per contract or max loss
The greater value for the Sept 25 Put is number 1 so the margin is:
0.25*29.11 - 4.11 + premium = $3.18 + premium
So in order to use the $100K in your account you will be able to sell:
100000/(3.18*100) = 314.46
Lets round to 314 contracts.
All things equal to the original example, the P/L on July31 for your 314 contracts is now $-95770. You are only left with less than $5K in your account and scrambling to find the money to comply with a margin call of:
(0.25*21.1 - 3.18)*314*100 = $2.10*314*100 = $65783
So now you need more than $65K just to be allowed to keep the contracts but you only have $5K left in your account and now you are panicking. However the worst scenario is if you are assigned as you clearly don't have the money to pay for the shares and your broker might buy and sell them at a substantial loss for you. Not to mention the 90 day freeze in your account.
In the meantime the credit spread owner is taking a good hit but he still has lots of money in his account and will live to see another day.
I hope that this time the situation is clear to you. And again, writing puts on cash secured account is not a big deal, but using margin, well you can see now how bad things can go if you are not prepared even using a Broker like Schwab that has very high margin reqs compared to the rest.