Nasdaq to launch 23/5 trading on December 6, with only one hour of market closure per day.

Nasdaq will launch its "23/5" trading regime on December 6 at 9 p.m. ET, extending U.S. equities trading to 23 hours a day, five days a week, running from Sunday 9 p.m. ET through Friday 8 p.m. ET with a one-hour daily maintenance halt from 8 p.m. to 9 p.m. ET. The new overnight session (9 p.m. to 4 a.m. ET) joins the existing pre-market (4 a.m. to 9:30 a.m.) and after-hours (4 p.m. to 8 p.m.) sessions to form a "global trading session," with trades executed between 9 p.m. and midnight counted toward the next trading day. The regular 9:30 a.m. to 4 p.m. ET session and opening/closing auctions remain unchanged, and the closing price stays the official benchmark. On the risk side, the SEC has approved revisions to the LULD plan, requiring overnight orders to stay within a 20% price band around the reference price. The rollout remains contingent on the Securities Information Processor being ready and related SEC rule changes, making the SIP readiness timeline and any further SEC approvals the key items to watch.