Trading with S&P 500 options

External question — Quantitative Finance Stack Exchange Author: Andras Hidvegi Original post: https://quant.stackexchange.com/questions/47454 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Could someone help me who has experience with trading S&P 500 options? I am curious about any liquidity trends (if OTM, ATM, ITM are the most liquid, and with what kind of maturity), and the average bid-ask spread on the option contracts. Also, any comments on the usability of trading platforms (like Interactive Brokers) would be appreciated.