Finance:Extended-hours trading
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Extended-hours trading (or electronic trading hours, ETH) is stock trading before or after the trading day regular trading hours (RTH) of a stock exchange, i.e., pre-market trading or after-hours trading.[1]
Market makers and specialists generally do not participate in after-hours trading, which can limit liquidity.[2]
Since 1985, the regular trading hours for major exchanges in the United States, such as the New York Stock Exchange and the Nasdaq stock market, have been from 9:30 a.m. to 4:00 p.m. Eastern Time (ET).[3] Pre-market trading occurs from 4:00 a.m. to 9:30 a.m. ET, although the majority of the volume and liquidity come to the pre-market at 8:00 a.m. ET.[4][5] After-hours trading on a day with a normal session occurs from 4:00 p.m. to 8:00 p.m. ET.[5] Overnight trading occurs from 8:00 p.m. to 4:00 a.m. ET, and only via electronic communication networks (ECNs) as opposed to stock exchanges.[6]
Trading outside regular hours is not a new phenomenon, but used to be limited to high-net-worth investors and institutional investors like mutual funds.[7] The emergence of private trading systems known as electronic communication networks (ECNs) has allowed individual investors to participate in after-hours trading. Extended-hours trading is all processed through ECNs including NYSE Arca.[8] For instance, the Blue Ocean Session is an overnight trading session available Sunday to Thursday on the Blue Ocean Alternative Trading System (Blue Ocean ATS; BOATS) since June 2021.[9][10][11] Yahoo Finance began displaying BOATS pricing data circa June 2025.[12]
Financial Industry Regulatory Authority (FINRA) members who voluntarily enter quotations during the after-hours session are required to comply with all applicable limit order protection and display rules (e.g., the Manning rule and the SEC order handling rules).[13]
Risks and limitations
Compared to trading during regular hours, extended-hours trading comes with additional risks. There is typically less volume in extended-hours trading compared to regular hours, which generally implies there will be less liquidity, wider bid–ask spreads, and greater volatility in extended-hours trading.[7] There is no guarantee that prices will carry over between regular sessions and extended-hours sessions as one ends and the other begins.[7] The ratio of professional traders to retail investors participating in extended-hours trading may be greater than during regular hours,[7] thus increasing the risk that the former can exploit the latter.
Many extended-hours ECNs only allow placing limit orders and not other types of buy/sell orders, decreasing flexibility for traders.[7] Access to these ECNs is also somewhat balkanized. Any given broker might only provide its clients access to certain extended-hours ECNs, thus decreasing liquidity within each ECN.[7]
See also
- Trading day
- Stock exchange halts and suspensions
- List of stock exchanges
- List of stock exchange trading hours
References
- ↑ "Extended Trading". https://www.nasdaq.com/market-activity/quotes/extended-trading.
- ↑ "After Hours Trading". 19 July 2016. https://www.investorsunderground.com/after-hours-trading/. Retrieved 11 November 2016.
- ↑ "About Us: History". NYSE. https://www.nyse.com/about/history/timeline_1980_1999_index.html. Retrieved 2007-04-11.
- ↑ "Pre-Market Trading". 19 July 2016. https://www.investorsunderground.com/pre-market-trading/. Retrieved 11 November 2016.
- ↑ 5.0 5.1 "US & Nordic Stock Market Schedule". 2026. https://www.nasdaq.com/market-activity/stock-market-holiday-schedule.
- ↑ Gratton, Peter (19 February 2026). "Overnight Trading: Definition, How It Works, and Example". Investopedia. https://www.investopedia.com/terms/o/overnighttrading.asp.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 "After-Hours Trading: Understanding the Risks". 4 November 2008. https://www.sec.gov/investor/pubs/afterhours.htm.
- ↑ "stock exchange | Definition, Meaning, History, & Facts | Britannica". https://www.britannica.com/topic/stock-exchange-finance.
- ↑ "Frequently Asked Questions". 2026. https://blueocean-tech.io/faq/.
- ↑ "Blue Ocean ATS (BOATS)". Intercontinental Exchange. 2026. https://developer.ice.com/fixed-income-data-services/catalog/blue-ocean-ats-boats.
- ↑ "Corporate Fact Sheet". 2026. https://blueocean-tech.io/corporate-fact-sheet/.
- ↑ "Yahoo Finance Expands Global Coverage with New UK-Based Programming and 24/5 Market Data" (Press release). Yahoo Inc. 26 June 2025. Retrieved 2026-09-25.
- ↑ Barclay, Michael J.; Hendershott, Terrence (Winter 2003). "Price Discovery and Trading After Hours". The Review of Financial Studies (The Society for Financial Studies) 16 (4): 1041–1073. doi:10.1093/rfs/hhg030. ISSN 0893-9454. https://faculty.haas.berkeley.edu/hender/after_hours_price_discovery.pdf.
Further reading
- Lachance, Marie‐Eve (6 July 2023). "Night trading: Lower risk but higher returns?". Review of Financial Economics 41 (4): 347–363. doi:10.1002/rfe.1180. ISSN 1058-3300.
External links
- "Trade After-Hours". Invest FAQ. 31 May 2019. http://www.invest-faq.com/articles/trade-after-hours.html.
This article incorporates public domain material from websites or documents of the United States Government.
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