In finance a share is a unit of account for various financial instruments including stocks, mutual funds, limited partnerships, and REIT's. In British English, the usage of the word share alone to refer solely to stocks is so common that it almost replaces the word stock itself.

A share is one of a finite number of equal portions in the capital of a company, entitling the owner to a proportion of distributed, non-reinvested profits known as dividends and to a portion of the value of the company in case of liquidation. Shares can be voting or non-voting, meaning they either do or do not carry the right to vote on the board of directors and corporate policy. Whether this right exists often affects the value of the share.