I consider opening EFP positions (at IB) and holding until expiration in order to capture discounts or premiums. I also consider using high leverage (if I correctly understand, the margin requirement is only 5%). I am trying to understand the risks â for loss, and for unexpected increases in margin requirements that might create havoc if the account is highly leverage. So far I figured out the following: A. for capturing a significant SSF discount with a short stock, long SSF on a hard to borrow stock: IB might close the short of the stock position before expiration, and the forced buy will create an immediate requirement for significantly higher margin, and leave a naked long stock position. This could be a problem if I miss such notification (or IB does not send me one â that happened); and when I become aware of it and liquidate the SSF, pricing might be bad. Another risk: Short borrowing fees might be much higher than the indicative rate. Also a very unusual, huge increase in stock value will increase margin requirement. B. For capturing premium with long stock short SSF: If the company does not pay expected dividend â a small loss. Also if the stock rockets, increase in margin requirement. - Other risks and considerations I am missing? - Will I have any problem of potential loss or unexpected margin requirement in case of an anomaly, like bankruptcy, acquisition, or trading halt? I have noticed a couple of times a relatively high SSF discount on a stock that does not have high borrow rate â and I wonder if this reflects some risk or consideration I am missing.