Sometimes you have to explain this to young people or people unfamiliar with the stock market.
- Why would a company want to be a stock company?
- Why would a person want to trade stocks?
- How does a stock market help society?
The stock market is just like any other market, but stocks are bought and sold here. Just like you buy and sell your electronics at the electronics market, this is a place where buyers and sellers come together to buy and sell shares or stocks or equity, no matter what you call it.
What are these shares? A share is nothing but a portion of ownership of a company. Suppose a company has 100 shares issued to it, and you were sold 10 out of those, it literally means you are a 10% owner of the company.
Why do companies sell shares? Companies sell shares to grow or expand. Suppose a business is manufacturing or producing and selling goods or services that are high in demand, the owners would want to take advantage of it and increase the production of his goods or services. And in order to increase production he would need money to buy land or equipment or labor, etc. Now either he could go get a loan by pledging something, or he could partner with someone who could give him money in exchange for some portion of the ownership of the company. This way, the owner gets the money to expand his business and make more profit, and the lender gets a portion of profit every time the company makes some. Now if the owner decides to sell shares rather than getting a loan, that's when the stock market comes into the picture.
Why would a person want to trade stocks? First of all, please remember that stocks were never meant to be traded. You always invest in stocks. What's the difference? Trading is short term and investing is long term, in very simple language. It's the greed of humans which led to this concept of trading stocks. A person should only buy stocks if he believes in the business the company is doing and sees the potential of growth.
Back to the question: a person would want to buy stocks of the company because:
How does a stock market help society? Look around you for the answer to this question. Let me give you a start and I wish everyone reading this post to add at least one point to the answer.
This book covers the history of financial instruments. It covers the rise of money, the history of bonds and stocks, insurance and hedge funds, real-estate, and the spread of finance across the world. It is a great introduction to finance, though its focus is very definitely on the history. It does not cover more advanced topics, and will not leave you with any sort of financial plan, but it's a great way to get a broad overview and historical understanding of money and markets. I strongly recommend both the video and the written or audio version.
In finance, form is function, and while a reason for a trade could be anything, but since the result of a trade is a change in value, it could be presumed that one seeks to receive a change in value.
There may have been more esoteric examples, but currently, possession of a company (total ownership of its' assets actually) is delineated by percentage or a glorified "banknote" frequently called a "share". Percentage companies are usually sole proprietorship and partnerships, but partnerships can now trade in "units". Share companies are usually corporations.
With shares, a company can be divided into almost totally indistinguishable units. This allows for more flexible ownership, so individuals can trade them without having to change the company contract.
Considering the ease of trade, it could be assumed that common stock contract provisions were formulated to provide for such an ease.
Motivation to trade
This could be anything, but it seems those with the largest ownership of common stock have lots of wealth, so it could be assumed that people at least want to own stocks to own wealth.
Shorting might be a little harder to reason, but I personally assume that the motivation to trade is still to increase wealth.
Social benefit of the stock market
Assuming that ownership in a company is socially valuable and that the total value of ownership is proportional to the social value provided, the social benefit of a stock market is that it provided the means to scale ownership through convenience, speed, and reliability.