SEC Trading and Markets Division Jamie Selway: Market System to Change to 23×5 on December 6
Jamie Selway, head of the SEC's Trading and Markets Division, stated at the 24-hour trading roundtable that the stock market data infrastructure will expand to a 23×5 operation on December 6, allowing multiple approved exchanges to offer trading during this period.
Currently, four alternative trading systems provide overnight trading. The Depository Trust & Clearing Corporation has been clearing stocks on a 23×5 basis since June, and FINRA's trade reporting facility has also extended its hours. Arrangements will continue to evolve after December 6, with the possibility of further extending to a 24×7 operation.
The division supports these preparations and urges investors and issuers to keep up with the changes. The analysis office will present reports on overnight and cross-time-zone transactions, characteristics of stocks participating in overnight trading, and behavior of cross-time-zone participants. Selway views this extension as a response to the demands of retail and overseas investors, potentially being the last systematic extension of trading hours.
Mechanically, this is a supply switch aligned with the market and clearing clocks: without an official SIP, overnight transactions can only occur in alternative systems without a unified best quote; once the SIP is operational, approved exchanges can write overnight orders into the public market. Beneficiaries include licensed delayed trading exchanges and brokers needing official quotes for best execution; those under pressure include overnight ATS relying on dark pool spreads and issuers yet to complete disclosure and oversight. Funds will not suddenly relocate on December 6, but compliant order flow will have a referenceable official clock.
Source: Public Information
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Atkins discussed growth and tokenization, Peirce addressed best execution and EDGAR closing, while Selway managed the calendar. Clearing began in June, with market alignment in December; the five-month interim was a transition of "clearing possible, no unified market." This is a standard regulatory step to upgrade alternative systems to exchange products: first make the infrastructure irreversible, then allow venue competition.
The capital path involves capturing overnight orders after fixed costs are sunk. The SIP and NSCC transformation is shared across the market, with incremental revenue initially benefiting a few liquid stocks and cross-border retail. The 24×7 possibility is noted rather than a commitment, as Sunday maintenance windows and corporate actions are still stuck in batch processing. Tokenization is mentioned by the chair for borrowing securities, but has not yet been prioritized for December 6.
Comparatively, options settlement precedes stock T+1, and futures night trading precedes official spot market quotes: clock reforms always race among clearing, data, and disclosure systems. The industry is at a stage where the data layer is about to merge with the clearing layer, while the disclosure layer has yet to start.
Structural judgments belong to regulatory changes. The mechanism is that once unified quotes cover overnight, the best execution obligation shifts from "optional participation" to "must prove quotes are comparable"; the information advantage of ATS is diluted by the SIP, and the nighttime value of exchange licenses increases. Whoever can quote referenceable buy and sell orders on December 6 will temporarily gain overnight pricing power.
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- Clearing opens first, market follows; that interim period is a testing ground without official prices.
- Once the clock is written into the SIP, best execution can no longer be ignored.
- While 24×7 remains a possibility, the real delivery is the 23×5 on December 6.