Corporate & Securities Blog

On December 6, 2026, Nasdaq and several other U.S. national securities exchanges will add an overnight trading session from 9:00 p.m. to 4:00 a.m. ET, Sunday through Thursday, to existing trading hours of 4:00 a.m. to 8:00 p.m. ET—extending the trading day to an almost-continuous 23 hours, 5 days a week. A one-hour trading pause will remain each weeknight from 8:00 p.m. to 9:00 p.m. ET to complete system maintenance and clear trades. The SEC has conditionally approved “23/5” trading for the following exchanges: Nasdaq, NYSE Arca, 24X, Cboe EDGX, and MEMX, subject to the consolidated market data processors (SIPs) being ready to support overnight quotes and trades.

For decades, public companies have relied on the overnight market closure as a window to release earnings results, process corporate actions, and make other material announcements before trading resumes. Under the new schedule, that buffer will shrink to just one hour, and news released after the traditional trading day may reach an active market almost immediately.

Key features of the new framework are summarized below:

• Limited Overnight Functionality. Only limit orders will be accepted overnight, and temporary static “Overnight Price Bands”—set 20% above and below reference prices—will cap trading prices to prevent extreme volatility.
• Mandatory Corporate Action Halts. For nine categories of corporate actions, including stock splits, large dividends, mergers, spin-offs, de-SPACs and ticker symbol or CUSIP changes, listing exchanges will implement a mandatory halt for the affected security beginning at 8:00 p.m. ET on the evening before the action takes effect through the overnight trading session. Securities subject to the mandatory halt would then reopen at 8:00 a.m. ET.
• Market-Wide Circuit Breakers Preserved. Even as trading hours expand, listing exchanges will maintain existing circuit breaker rules, which provide for U.S. market-wide trading halts during a severe market decline. Under the new 23/5 trading schedule, a Level 3 halt—the most severe level—will continue to trigger a trading suspension until at least 4:00 a.m. ET the next day.
• Investor Risk Disclosures. Brokers must warn customers about overnight risks, including lower liquidity, changing prices, wider spreads, and an “exaggerated effect” from potential news announcements.

At the SEC’s September 17, 2026 roundtable on 24-hour trading, Chairman Atkins invited issuers to comment on how extended hours may affect corporate actions, the dissemination of material information and SEC filings made during EDGAR filing hours. Commissioner Peirce asked whether issuers will need to change their current practice of releasing news before or after core trading hours.

Practical Implications for Issuers

Once 23/5 trading commences, a press release issued at 4:05 p.m. will now be traded on for much of the night, including in relatively thin markets where retail and non-U.S. investors may be active. As a result, reporting companies should reassess the timing of their earnings releases and Current Reports on Form 8-K, as well as how they satisfy Regulation FD’s broad public-dissemination requirements. Boards and senior management should also anticipate stock-price reactions and investor or media questions to arise overnight, rather than exclusively during the next business day.

In addition, issuers should review their insider trading policies to verify whether blackout periods or trading-window openings are tied to “trading days” or the “market close,” as those terms may need to be redefined in light of the expanded trading schedule. Likewise, many corporate and transactional documents assume a single trading day ending at a 4:00 p.m. close, and references to “closing price,” “trading day,” or “after market close” may yield unintended results under the 23/5 trading schedule. Companies should therefore also reevaluate (i) equity plans and award agreements, including fair market value definitions used to set exercise prices, vesting triggers and settlement mechanics; (ii) indentures, convertible notes and credit agreements with price-based conversion features or covenants; (iii) M&A documents, including earnouts, material adverse change definitions and stock consideration pricing; (iv) vendor and other operational contracts with market-based pricing formulas; and (v) D&O and other insurance policies with coverage triggers or valuation provisions tied to market pricing or trading days.

Finally, companies should revisit Rule 10b5-1 plans and broker instructions to confirm whether trades may execute overnight and how the limit-order-only rules will apply going forward. If an adjustment to a Rule 10b5-1 trading plan is made in response to the new 23/5 cadence—for example, to change when trades may occur—issuers should keep in mind that changing a plan’s amount, price, or timing is generally treated as adopting a new plan and triggers a new cooling-off period.

Ahead of the December 6, 2026 launch, reporting companies should (i) confirm earnings and material news release timing and disclosure controls; (ii) update insider trading policies, pre-clearance procedures and blackout definitions; (iii) confirm with plan brokers how existing Rule 10b5-1 plans will operate overnight before making any changes; (iv) coordinate the timing of planned corporate actions with their listing exchange; and (v) brief the board and senior management on the new overnight trading session.