Why on some days is there a price gap on the S&P futures market. Meaning why is there a major difference in the closing price and opening price. Example on 2/18/2022 market closed at 4343.5 and on 2/22/2022 it opened at 4324.5 almost 20-point difference between close and open.

  • $\begingroup$ 2/19 and 2/20 were weekend days and 2/21 was a partial holiday (Presidents' Day) (so no trading but plenty of news happening in Eastern Europe among other places! Stocks got repriced.). $\endgroup$
    – nbbo2
    Commented Feb 23, 2022 at 16:44
  • $\begingroup$ No that is not the answer it happens on other days when not weekend for example on 2/1/2022 market closed at 4535 and opened at 4552 the futures market is only closed for 1 hour on those days so what would cause a 17 pt jump $\endgroup$
    – Wray
    Commented Feb 23, 2022 at 17:31
  • 2
    $\begingroup$ 0n 2022/02/01 the close of 4535.00 is the settlement price, which is measured at 4pm Eastern Time. The futures market does not truly close but keeps trading at a reduced volume until 5pm. At 5pm the price was 4549.50, a big increase likely because of news (earnings?) between 4 and 5pm. Then the market closed for 1 hour and reopened at 6pm at 4552.5 like you said. But the big change was between 4pm and 5 pm with the market still trading. The term "closing price" is misleading and really refers to the settlement price, at 4pm. $\endgroup$
    – nbbo2
    Commented Feb 23, 2022 at 17:59

1 Answer 1


The mechanisms behind the determination of 'special' prices like 'close', 'open' etc are non-trivial and vary from security to security. For example, 'open' prices can be (but not always) the average from a special auction period, rather than just the mid snapped at certain time. To fully understand the origin of these prices, refer to the exchange's rulebook.


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