If you start studying the capital markets you'll quickly learn just how little you've known about the economy before. Look at any object on your desk - know how was that thing made? Someone out there has manufactured the thing, there was a few if not a few dozen corporations involved.
Because filing the form S-1 comes quite a bit before the actual start of trading. S-1 is a prospectus, lets investors familiarize themselves with the offering.
I'd also add that this is just NASDAQ. There's a lot of other exchanges across the world.
Though, obviously, offerings in other (foreign) markets won't necessarily file S-1s because S-1 is a concept of the United States' Security and Exchange Commission (SEC).
https://www.nasdaq.com/market-activity/ipos
If you start studying the capital markets you'll quickly learn just how little you've known about the economy before. Look at any object on your desk - know how was that thing made? Someone out there has manufactured the thing, there was a few if not a few dozen corporations involved.