J'ai la réponse :
"
What is the exchange minimum margin requirement on SSF positions?
Overview:
In the case of a long or
short SSF, the exchange margin requirement is equal 20% of the underlying value of the contract (initial and maintenance margin)
In the case of a hedged position (e.g., High or Low Synthetic strategy) in which a clilent is long (
short) a security futures contract and
short (long) the underlying security, the required maintenance margin would be equal to 5% of the instrument having the higher current market value.
"
Source : https://ibkr.info/article/97