U.S. stock exchanges are promoting round-the-clock trading—will the risk of after-hours price manipulation soon come to an end?

The global financial markets are accelerating their digital transformation. Major institutions such as the New York Stock Exchange and Nasdaq are actively working to relax trading-hour restrictions, moving toward all-day, around-the-clock trading. Market analysis suggests that this is not only aimed at increasing fee revenue; the goal is to break the current after-hours pricing power monopolized by brokers. By increasing liquidity, it seeks to reduce the occurrence of artificial manipulation and the malicious triggering of stop-loss orders. Traders and retail investors may become the biggest beneficiaries under the mechanism changes.

Traditional market-close rules create pricing loopholes

For a long time, the closing arrangements of traditional securities exchanges have created special profit opportunities for some intermediary institutions. After the 4:00 p.m. market close in Eastern Time, the market enters a period of scarce liquidity, and the bid-ask spread widens accordingly. Quantum Economics CEO Mati Greenspan noted that, in the absence of a transparent trading environment, a small number of brokers control the first tradable price when trading reopens. This highly concentrated pricing power means intermediaries may, after the release of major news, deliberately guide prices through the opening auction, thereby triggering clients’ stop-loss orders, causing investors to close positions at unfavorable prices. Meanwhile, the broker on the other side profits. In after-hours environments with insufficient liquidity, this kind of behavior becomes a gray-area operation that is difficult to detect through regulation.

Regulatory academic research confirms post-market manipulation concerns

Academic circles and regulatory bodies also have doubts about the efficiency of non-standard trading hours. Joint research by the University of California, Berkeley, and the University of Rochester shows that the price discovery efficiency of after-hours trading is far lower than during regular sessions. The main reason is that sparse trading volume hinders the speed of information response. In addition, in enforcement actions and reports by the U.S. Securities and Exchange Commission (SEC) and the Financial Industry Regulatory Authority (FINRA) between 2025 and 2026, they repeatedly mentioned deceptive trading practices such as Spoofing and Layering, which are especially common in more volatile securities. FINRA’s regulatory oversight report emphasized that some firms failed to establish reasonable regulatory systems to identify manipulation in after-hours trading, indicating that the current trading window does carry structural risks and a lack of transparency.

Around-the-clock trading shifts power back to retail investors

Changes to the around-the-clock trading model will shift power away from intermediary institutions and back to traders. In today’s electronic markets, institutional players equipped with high-performance computers and algorithms have an edge in reaction speed, while retail investors are often at a disadvantage during market closures when major international events occur, because they can’t act immediately. Pranav Ramesh, head of quantitative options research at Nasdaq, pointed out that during low-liquidity trading periods, investors lack reference points for assessing execution quality. If around-the-clock trading is implemented, it will eliminate the trading vacuum on weekends or at night, enabling all investors to respond in real time to market news. During recent conflicts in the Middle East, the volume of gold and oil derivatives traded on the decentralized exchange Hyperliquid surged, proving strong market demand for trading in non-traditional time periods.

Major exchanges race to roll out 24-hour trading services

Faced with competition from digital asset exchanges and decentralized platforms, U.S. traditional finance giants are accelerating their transformation. The New York Stock Exchange has submitted an application to the SEC, seeking approval for its around-the-clock trading plan; Nasdaq also announced a similar blueprint toward the end of last year. In the derivatives space, the Chicago Mercantile Exchange is expected to launch 24-hour cryptocurrency futures trading in 2026, and the Chicago Board Options Exchange has expanded the trading hours of U.S. stock index options to 5 days per week, 24 hours per day. Although it remains to be seen whether around-the-clock trading can completely eliminate price manipulation, improving market continuity through better制度（institutional design） has become an irreversible global financial market trend. This not only weakens intermediaries’ influence during certain time windows, but also gives investors greater freedom to hedge.

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