A stock is a financial instrument that represents ownership in a company or corporation and represents a proportionate claim on its assets (what it owns) and earnings (what it generates in profits). Stocks are also called shares or a company’s equity.
Stock ownership implies that the shareholder owns a slice of the company equal to the number of shares held as a proportion of the company’s total outstanding shares. For instance, an individual or entity that owns 100,000 shares of a company with one million outstanding shares would have a 10% ownership stake in it. Most companies have outstanding shares that run into the millions or billions.