What is the stock market, in simple terms?
A marketplace where people buy and sell small pieces of companies. Prices come from whatever buyers and sellers agree on, minute by minute.
Picture a farmers’ market, except the stalls sell slices of companies instead of vegetables. Anyone can walk up and buy a slice of Apple or Coca-Cola, and anyone who owns one can sell it. The "stock market" is just the collective name for all those stalls, which today are computer systems run by exchanges like the NYSE and Nasdaq.
A company gets there by selling shares to the public the first time, in an IPO, to raise money. After that, the company is mostly out of the picture. Almost every trade you see is one investor selling to another; the company does not get the money and does not have to approve the sale.
Prices come from nothing more mysterious than what the last buyer and seller agreed on. If more people want to buy than sell, the price ticks up until enough sellers appear. If more want out, it ticks down. News, earnings and moods all feed into that balance, which is why prices move all day.
When someone says "the market was up today," they usually mean an index like the S&P 500, which averages the prices of 500 big companies into one number so you can see the overall direction at a glance.
Informational only, not financial advice. Updated September 4, 2026.
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