There are numerous exchanges in the US. The trading is mostly done on NYSE / NASDAQ although some others do trade a meaningful volume. What happens when you cl

There are numerous exchanges in the US. The trading is mostly done on NYSE / NASDAQ although some others do trade a meaningful volume. What happens when you click in your app on 'buy' or 'sell' button is a different story. Mostly, it will never trade on an exchange actually. Especially in the US. Look up 'payment for order flow' if you're interested in it. Short version is - retail trades don't have any 'alpha' - you can just collect the spread executing it. And companies are willing to pay for that.