A measurement of the relationship between the risk of an individual stock or stock portfolio and the risk of the overall market. The beta is a measure of the sensitivity of an investment’s return to market movements. A diversified portfolio of high beta stocks is more risky than a diversified portfolio of low beta stocks.
Bid offer spread
The difference between the bid and offer prices of a security.
Bid price
The price at which a buyer has offered to purchase a security or commodity.
Bid/ask spread
The difference between the price at which a Market Maker is willing to buy a security (bid), and the price at which the firm is willing to sell it (ask). The spread narrows or widens according to the supply and demand for the security being traded.
Big Board
A popular term for the New York Stock Exchange.
Big figure
A market expression for the part of the price which is the least significant in terms of quotation movement.
Black box trading
A proprietary computerised trading system whose formulas and calculations are not disclosed or readily accessible. Users enter information and the system utilises pre-programmed logic to return output to the user, which may include trading signals and other data.
Black-Scholes model
An option pricing formula initially derived by Fisher Black and Myron Scholes for securities options and later refined by Black for options on futures.
Block
A large amount of shares, normally 10,000 shares or more.
Block crossing network
An Alternative trading system (ATS) that handles large blocks of stock for institutions, which may be matched in a "dark pool".
