Overnight options let a trader buy protection, reduce an existing hedge or express a volatility view before the opening auction absorbs the news. Interactive Brokers already supports overnight Cboe index options for customers with the required permissions. In May, SPX overnight volume had set a then-record of 171,000 contracts, as shown in the earlier Cboe options-volume data. SPX overnight volume alone increased 15% from May to July, based on the two Cboe releases. tastytrade said the session recently exceeded 4% of total SPX options volume, up from about 3% several months earlier.