You don't even actually match up buyers and sellers on the public markets anymore for stocks. Individuals (from retail to institutional investors) buy and sell to market makers; later, when settling, market makers will pair up with brokers when clearing the funds.
So it'd be up to the market makers to not fuck up and sell at $1. If not, it's their liability.
So it'd be up to the market makers to not fuck up and sell at $1. If not, it's their liability.