What is a share?
A stock, also called an equity, is a security that gives its holder part ownership of a company.[S1] A share is one unit of that ownership.
Why do companies sell shares?
Companies issue stock to get money. The SEC's investor site lists paying off debt, launching new products, expanding into new markets, and enlarging or building facilities.[S1]
A company's first sale of shares to the public is generally called an initial public offering, or IPO.[S4] To see what a company files before its IPO, read how to read an S-1.
New shares are sold in the primary market, where the issuer receives the money.[S2] Existing shares are bought and sold in the secondary market.[S3]
Stocks in public companies are registered with the SEC. In most cases, these companies must file reports every quarter and every year.[S1]
Why do share prices move?
Share prices change throughout each trading day. FINRA, a US broker regulator, says they reflect investor demand and the state of the markets.[S5]
FINRA says strong demand, from many investors wanting to buy a stock, tends to raise its price. It also says demand typically reflects the company's future prospects.[S5]
Some causes sit inside the company, such as a faulty product. Others are outside its control, such as political or market events.[S1]
Stock prices move down as well as up. There is no guarantee a company will do well, so money invested in stocks can be lost.[S1]
What do you actually own?
Common stock entitles its owner to vote at shareholder meetings and to receive dividends.[S1] A dividend is a portion of a company's profit paid to shareholders.[S6]
A company may pay dividends, but it does not have to. The amount is not guaranteed.[S5]
Preferred stock usually has no vote. Its holders receive dividends before common stockholders and rank ahead of them in a bankruptcy.[S1]
Ranking matters if a company goes bankrupt and its assets are sold. Bondholders are paid first, then preferred holders.[S1]
Common stockholders get whatever is left, which may be nothing.[S1]
Share classes can also differ. A company may issue classes with different voting rights or dividend policies, as dual-class shares explains.[S5]
Example: what does one Amazon share represent?
A vote. Amazon's 2026 proxy says it has a single class of common stock, where "one share equals one vote."[S7]
A slice of the profit, on paper. Amazon's net income for its fiscal year was $77.7B (FY2025). Net income is the profit left after all expenses and taxes.[S9]
Per share, that year's diluted earnings were $7.17 (FY2025). "Diluted" means the count includes the extra shares that stock awards could create.[S8]
That figure is an accounting share of profit, not a payment to shareholders. The financing section of Amazon's FY2025 cash flow statement has no dividend line.[S8]
A small part of the whole company. One share is one part of all the shares outstanding: 10,786.3 million (on Jul 22, 2026).
A price set by trading. Amazon's closing price on Nasdaq: $240.35 (price as of Oct 30, 2026).[S10]
Price times shares gives its market cap, using the Nasdaq closing price on the date shown: $2.60T (price as of Oct 30, 2026).[S10]
The Amazon stock page shows where these figures come from. To see how the profit line is built, read revenue, profit and cash flow.