What happen in Interactive with cash settlement contracts ?

[FSU]

Just study this ShortCall trade and tell me what happens if the underlying moves to 160, ie. up +60%.
Do you still mean no new/additional funds required? No margin call?
https://optioncreator.com/staiv5t
(S=100 K=100 t=1 IV=30 --> Pr=11.9235)

You're talking about 2 different things. Of course you may need additional margin if an index moves 60% against you and you are short options naked. You would have lost a lot of money here.

The OP was asking about not closing cash settled options before expiration. With cash settled indexes there is no pin risk, no exercise risk, you don't have to come up with the cash to pay for shares as if it was an equity option. So, if you are long/short a spread you have real defined risk. If you are naked short an option (he didn't specify that) yes, your losses can be great. You have expanded the original question to "can my margin requirement change if I am naked short an option and it moves against me"

 

[earth_imperator]

FSU, this thread had already ended for me b/c I had assumed options but the OP was meaning futures. Now you have reactivated the discussion and I was careless not to remember that it's about futures trading.
And: in the OP it's not stated that it's about spread trading.
Long story short: I'm out b/c I don't and can't talk about futures as I'm an options guy only.

 

[FSU]

FSU, this thread had already ended for me b/c I had assumed options but the OP was meaning futures. Now you have reactivated the discussion and I was careless not to remember that it's about futures trading.
And: in the OP it's not stated that it's about spread trading.
Long story short: I'm out b/c I don't and can't talk about futures as I'm an options guy only.

The OP never mentioned futures, it was brought up by another poster. I was talking about options not futures. Everything I said was concerning options. But I agree, no real need to continue the conversation with you.