Bid/Ask/Spread Plots
The bid and ask are critical values for traders. The spread between them is vital to assessing the value and liquidity of an issue. Below are plots related to the Bid, Ask and Spread.
1. Bid/Ask/Mid Plots
The plot of the Bid is a history of the best offer for a stock. This is the highest a trader has been willing to pay for the stock at a given point.
The plot of the Ask is a history of the lowest asking price for a stock. This is the least a trader has been willing to take for the stock at a given point.
The plot of the Mid is a history of the midpoint between Bid/Ask for any period of time.
2. Bid/Ask Spread Plots
The Bid/Ask Spread is the amount by which the ask price exceeds the bid price expressed as a net value. The Bid/Ask Spread % is the amount by which the ask price exceeds the bid price expressed as a percentage.
The Spread is the measurement of market liquidity. Markets that are more liquid will be reflected in lower spreads than those more thinly traded. Each plot is a history of the spread for any period of time.
All Bid/Ask related values can be plotted for both stocks & options (with real-time data feed).
Read more about using the Bid/Ask/Spread for trading on Investopedia