An investor owns a piece of the company when he/she buys what?

certificates of deposit
stocks
bonds
mutual funds

stocks

Explanation:

The worth or value of a company is subdivided into small units known as shares, stock, or equity. Each unit of a stock represents a small proposition of the company. Holders of the stocks are commonly referred to as the shareholders, are the owners of a company.

A company's ownership can be acquired through the purchase of shares at the stock exchange. Founders of the company are also shareholders, hence owners as long as they have not sold their shares.  As owners of the business, shareholders are entitled to partake in the firm's profits. They participate in managing the business by electing directors who, in turn, appoint top management of the company.