According to BlockBeats, on September 17th, SEC Commissioner Hester M. Peirce, speaking at a roundtable discussion on 24-hour trading in US stocks, pointed out that extended trading hours are taking shape in the form of 23-hour sessions and a five-day trading week. Although this has existed for years on some ATSs (Alternative Trading Systems), extended trading hours still account for less than 1% of total stock trading volume on the NMS (National Regulatory Market), and are highly concentrated on a small number of stocks. Over the past two years, both new entrants and traditional trading platforms have actively expanded their operating hours to respond to domestic and international demand. In terms of infrastructure, the NSCC switched its clearing operations to a 24/7 model in June, operating continuously from 8 PM Sunday to 8 PM Friday; the SEC approved an extension of SIP (Securities Information Processor) operating hours, with the new schedule launching on December 6th; the Commission also approved a market-wide price limit scheme during extended trading hours, and trading venues have established standards for handling corporate actions.

Peirce acknowledged that many market participants have mixed feelings about this shift, viewing it as an inevitable but not entirely welcome complication, worrying about thinner overnight order books, wider spreads, increased price volatility, and the compression of back-office operations, batch processing cycles, and critical IT maintenance to just one hour per night.

Peirce points out that beyond operational issues, there are more fundamental human concerns, such as sleep. Extended trading hours amplify concerns about data source disruptions at 3 a.m. or social media rumors depressing stock prices while headquarters are asleep. The US market is not pioneering new territory; it can learn from the foreign exchange market (which has been operating 24/7 for decades), the crypto market (which never sleeps), and the overnight index options and futures markets (generally 23/5). A South Korean trading platform also announced plans to extend trading hours last week.

Peirce raised a series of questions: What lessons can markets with continuous trading experience offer for the US stock market regarding liquidity, market making, manipulation, and cybersecurity risks? How can brokers fulfill their best execution obligations when liquidity is dispersed and spreads are wide? For asset managers, is choosing not to trade overnight still an acceptable fiduciary decision when liquidity and execution costs are unfavorable? Do issuers need to change their behavior? Currently, issuers typically file documents and release material information before and after the core trading session, while EDGAR documents filed after 5:30 p.m. are usually processed on the next business day. Should the SEC modify its system to ensure timely dissemination of corporate actions and material information overnight? Should the Commission provide guidance or relief to alleviate the burden of extended trading on issuers, especially smaller issuers?