Noticed that the daily closing price of options (at least the ones I checked) are different than the closing price at 16:00. Many seem to trade-or at least the price changes--up to 16:15. Could someone please explain 1) how that happens 2) can retail traders get in on it? I'm working on something which requires daily charts but if I'm not going to trade as the same time/prices it's going to muck things up. An example would be SPX120317C1375. The daily candle today shows a closing price of $14.00. But if you look at a 1 or 5 min chart it didn't reach 14 until 16:15. Thanks very much for any assistance.