A bid is an order to buy a stated quantity at a stated price or better. The highest bid in the book is the best bid, and it is one half of the quoted spread.
market microstructure · updated 2026-09-08
See also
Ask— An ask, also called an offer, is an order to sell a stated quantity at a stated price or better. The lowest ask is the best offer.…
Bid-ask spread— The bid-ask spread is the difference between the best bid and the best ask. It is the immediate cost of trading in and straight ba…
Order book— The order book is the live list of all outstanding buy and sell orders for an instrument, arranged by price, that a trading venue …