Question on US500 Options expirations

[SilentSniper]

Hi,

I've a question on the options expirations for the US500 index. I understand that, apart from the daily options which are the priced off, and settle into, the IG daily spot cash index product, but that the weekly, monthly, quarterly, options behave like futures options and are priced off, and settle into the next underlying futures market (not the spot cash). This is similar to how I trade futures options on the ES at a different brokerage account (schwab). So, for example, the Jan and Feb option expirations for the US500 will be priced off, and settle into the underlying March futures ES contract (subject, of course, to the special opening quotation system), and the July and August expirations will settle into the September futures product. (They do not settle to the spot cash daily US500 IG product.)  So, for example, if I sell a  Jan 3890 Call option, it will be in the money only if the ES March futures (ESH23) is trading above 3890, regardless of what the IG spot daily cash US500 product is trading at. Can someone at IG please confirm if this understanding is correct? If it is correct then is it possible someone could also explain also why IG index SB monthly Options for the US500 for Jan 23 and Feb 23 list different prices for the underlying product at the top of the options chains - it lists the Jan 23 options underlying product at 3851.49 and the Feb 23 underlying as trading at 3859.49 (as at 22:00 hrs on 1st Jan 23). It lists the March options underlying correctly at 3867.49 - which is the correct for the March ES futures product (ESH23). I don't understand why Jan and Feb and not also quoted at 3867.49?

Sorry for the long question!

Thanks, David