It may be comforting to know that this is not some “dark web” stock market thing going on. S&P 500: day and nightThe market closes at 4PM each day. But the S&P stock “futures” market is alive for most of the 24-hour period. The futures market for U.S. stocks rests on Friday night and opens again at 6PM EST on Sunday. Participants in the futures market, which is often very thinly-traded until close to market open each day, set the price for the S&P 500.

Source: Forbes September 20, 2020 12:56 UTC