Hi, It is known that generally the maximum loss of a calendar spread is the debit paid. Nonetheless, I think this is not true regarding calendar spreads on cash-settled index options such as the SPX, in which one can lose much more than the debit paid. For example, if I buy 1150 SPX Oct/Nov call calendar spread for 14.1 debit, and if the SPX October settlement value will be at 1200, I will be assigned on my short October call and incur a debit of 50, and if the SPX November settelement value will be at 1150 (or lower), my long SPX 1150 call will be worthless and therefore my loss for the entire spread will be 64.1 (14.1 debit initially paid plus 50 debit due to the assignment). However, such situation can never occur regarding physical delivery options such as the SPY, since whenever I am assigned on my short calls I can exercise my long calls. Am I missing something here? If not, why are traders willing to trade calendar spreads with cash-settled options and therefore pose themselves to virtually unlimited risk?