Raltin has a comprehensive list of features & factors that investors use in machine learning and quant models for investment and risk management. One of the features is the bid-ask spread of options for a given ticker. The bid-ask spread percentage is important for several reasons - 1) It gives us a clearer picture of the supply and demand of an asset. 2) It is the de facto measure of liquidity. 3) It helps us understand the costs of a trading strategy 4) and it can be used to identify potential trading arbitrage opportunities. Doing a consistent bid-ask spread measure across time for a given ticker is hard because of options expiry. Similar to Raltin’s VIX like implied volatility measure, we created a bid-ask spread measure across time to understand bid-ask spreads over time. The below table shows the median bid-ask spreads for 20 tickers with the most option volume for options closest to the 30 day At the Money (ATM) expiry. Raltin Pro and other institutional clients get access to historical bid-ask spread percentages across all tickers and moneyness. Please email raltin@raltin.com for more details and demo of our features / factors and portfolio back testing technology.