When do SPX options settle and expire?

In the TWS OptionTrader or TWS/Mosaic Option Chains window, click on the drop down menu that says SPX in the upper right corner of the option chains. Select SPXW as the Trading Class and the screen will change to the SPXW Weekly options. The rest of the available weekly expiries can be found by clicking on the…

The US overnight trading hours are 8pm ET to 3:50am ET Sunday to Friday.

• First trading session of week: Sunday 8pm to Monday 3:50am
• Last trading session of week: Thursday 8pm to Friday 3:50am…

The US Stock options that stop trading at the end of the regular trading day on the 3rd Friday of the month (considered Monthly option) are settled using the Composite Close (CC) price calculated around 16:00 EST. An option is expired after the OCC completes it's processing. The standard expiration date for US Stock options is the Saturday immediately following the 3rd Friday of the month…

The only action one can take to prevent being assigned on a short option position is to buy back in the option prior to the close of trade on its last trading day (for equity options this is usually the Friday preceding the expiration date although there may also be weekly expiring options for certain classes). When you sell an option, you provided the purchaser with the right to exercise which they generally will do if the option is in-the-money at expiration…