Mreh, it's all about order status and what you can and cannot do during those times is all. Here, start at page 8 and read on. (HALT = "Pause") https://www.cmegroup.com/globex/files/GlobexRefGd.pdf For the basic trader, this is not important in any way shape or form. "You can't trade futures when it is halted or closed" is all that matters for the majority of us. Easy rule.
It's not about intraday/overnight margin. It's about fees. It's about CME no longer keeping exchange closed on MLK.
Fascinating. What fee does the CME get extra by being in open status for half the day, on MLK, rather than close for the whole day? Sincerely yours, Curious George.
Exchange trading fees, of course. The volume is light, of course, but every little bit helps poor little CME Group. Same thing with Friday after Thanksgiving.
It is not an extra fee, just a normal fee, cost of doing business. And by the way, in that link you posted it shows a reduction in fees for certain folks trading in options. https://www.cmegroup.com/content/dam/cmegroup/notices/ser/2018/12/SER-8290.pdf