When you short a stock, you have to borrow the stock first, and then sell it. Obviously at some point you will buy back the stock, hopefully at a lower price so you make a profit, and then return the stock to the original owner.
When you naked short sell, you don't borrow the stock first, you just claim you do. Everybody trades pieces of paper without settling the trade. This might seem convenient but someone can abuse this.
For example, sell a billion shares in a stock which you don't own / have not borrowed, at a fire-sale price, thereby causing the share price of a company to crash because people start panicking once they see huge volumes being traded at a low price.
NYSE is owned by Intercontinentalexchange Group which is publicly listed.
> Like so many others, he believes bitcoin can free the world from the control of big banks and big government. “It helps us fight the machine,” he says.
I cringed reading this, mostly because normal people don't feel quite comfortable with sentiment like "fighting the machine."
Get outside and talk to some folks. Very few are friends of "the machine."