I have another naive question. On Thursday night and before Friday morning, after Trump posted on twitter saying he contracted Covid-19 around 12:50AM. The news media was saying the US stock market would fall when the market opened on Friday morning by looking at the future. I have never traded future, so I really don't know how you can look at the future when the market is not open. Is the future market still open even when the US stock market is closed? Does the media just look at S&P 500 future?
Most types of contracts begin trading at 6 PM EST on Sunday and close around 5 PM on Friday. Each sector has its own trading hours as well as the length of a trading break on week days (15 minutes to an hour) in the 4 PM to 5 PM area.
The futures don't predict the market. They are a reflection of the market. So when the news media was saying the US stock market would fall when the market opened on Friday morning, they were telling you what had already happened. If the futures recovered overnight then this 'prediction' would not come to pass.
For example, when it became apparent late on election night in 2016 that Trump was going to be elected, the DJIA futures were down over 1,000 points. By the next morning, all of the loss had been recovered and the DJIA ended up about 250 points that day.