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I was going to jump in and say, "Yeah, options trade till 4:15 EST," which I'd always heard. But then I wondered why they didn't stop at 4:00 like shares, so I asked Claude. Interesting history if you care to read it:
# First: Not All Options Trade Until 4:15
Only **certain ETF and index options** get the extra 15 minutes. These include SPY, QQQ, IWM, DIA, and index options like SPX, VIX, RUT, and NDX. Most equity and ETF option contracts trade Monday through Friday 9:30 AM to 4:00 PM ET — same as stocks.
The 4:00-4:15 window is called the **"Curb session"** on CBOE.
# Why the Extra 15 Minutes Exists
There are two main reasons:
**1. Contra-Exercise Risk.** This is the big one. The additional 15 minutes of live trading post-RTH close allows investors to close positions upon an after-market event that occurs during the expanded time window. Stocks keep trading after 4:00 PM, which means an option that was OTM at 4:00 could become ITM by 4:15 (or vice versa). Without that extra 15 minutes, you'd be trapped — watching your option flip from worthless to valuable (or the reverse) with no ability to act. This risk exists today when an options contract closes out-of-the-money but is exercised due to an event that moves the price of the underlying security after the RTH close, resulting in significant economic impact and potential tax consequences.
**2. End-of-Day Rebalancing and News.** Major market-moving events — earnings releases, economic data, Fed statements — often drop right at or just after 4:00 PM. Index and broad ETF option holders need the ability to react to these events rather than waiting helplessly until 9:30 AM the next day facing a potential gap.
# The Historical Twist
Here's the interesting part: all equity options used to trade every day until 4:10 PM. So historically, the stock market closed at 4:00 and ALL options had an extra 10 minutes. Over time, most individual stock options lost that extended window, while the major index and ETF options kept it (and extended it to 4:15).
# What's Coming
As we discussed in our SOXX extended-hours conversation, CBOE just got SEC approval to expand this further starting July 13, 2026:
* **Pre-market:** 7:30 AM – 9:25 AM for select equity options
* **Curb session:** 4:00 PM – 4:15 PM for select equity options
To qualify, the option class needs average daily volume of 150,000+ contracts, underlying market cap of $50 billion+, and underlying average daily volume of 10 million+ shares. So only the most liquid names — think NVDA, AAPL, MSFT, TSLA — will get extended hours initially.
# The Bottom Line
The 4:15 close exists because stocks keep moving after 4:00, and options traders need a brief window to manage the risk of their positions being affected by after-hours price action. It's a safety valve, not a convenience feature. The fact that it used to be universal (4:10 for all options) and was narrowed to just index/ETF products shows that the exchanges decided the risk was most acute for broad market products where portfolio-level exposure is highest

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