Bid Price

The bid price is the highest price that a buyer is currently offering to pay for a stock, option, or other security at a given moment. It sits on one side of every quote you see on a trading screen, paired with the "ask" (or "offer"), which is the lowest price a seller is willing to accept. Together the bid and ask make up the quoted market for that security.

When you place a market order to sell, you generally sell at the current bid, because that's what buyers are offering right now. The bid isn't a single fixed number set by an exchange; it's constantly updated as traders and market makers place and cancel orders, so it can move many times a second in an active stock.

The gap between the bid and the ask is called the spread. A small spread usually means a security is actively traded with lots of buyers and sellers close together in price; a wide spread often means the security is thinly traded, and it can cost you more to get in or out quickly. It's also worth remembering that the bid shown is usually just the best (highest) bid available — behind it there can be many other buyers waiting at lower prices, visible if you look at a Level 2 order book.

A common point of confusion: the bid is not "the price" of the stock in any single, official sense. A stock at any instant has a bid, an ask, and a last traded price, and these three numbers are often slightly different from each other.