The stock exchange is a market for the buying and selling of?

The stock exchange is a place where people can buy and sell certain things. Specifically, it is a market for buying and selling existing shares. Shares are pieces of ownership in a company, and they can be bought and sold like any other product. So, if you want to buy a share of a company, you can go to the stock exchange and find someone who is selling one. Conversely, if you want to sell a share, you can find someone who is willing to buy it from you. This is all done through the stock exchange. The other options listed in the question - monetary instruments, new shares, and treasury bills - are not what the stock exchange is specifically for. To learn more about this, please read the relevant sections of the recommended textbooks.