Major US stock exchanges are expanding trading hours to compete with 24-hour cryptocurrency platforms and global investor demand. Nasdaq and NYSE Arca plan to launch overnight trading on December 6, extending sessions to at least 23 hours a day, five days a week. The London Stock Exchange will begin LSE 24 in 2027, allowing trading from 5 p.m. to 7:50 a.m. London time.

Proponents argue this aligns equities with continuous markets like futures and foreign exchange. However, skeptics warn that removing overnight closures could lead to unexpected volatility and operational challenges. The International Monetary Fund has cautioned that continuous trading may leave regulators with insufficient time to intervene during a crisis.

With fewer traders active outside regular hours, investors may also experience lower trading volume. Retail brokerages like Robinhood Markets Inc. and Charles Schwab Corp. have already enabled overnight trading through alternative trading systems, though these still account for less than 1% of total US stock volume. The expansion represents a significant shift in how global investors access US assets.