Nasdaq Proposes Rule Change to Use CQS/UQDF for Night Session Quotation Data

The Nasdaq Stock Market LLC proposed amending Equity 4, Rule 4759(a), to specify the source of quotation data the exchange will use during its overnight trading session for equities.

In the proposal to the SEC, Nasdaq stated that during the Night Session (9:00 p.m. to 4:00 a.m. ET, Sunday through Thursday), it will use CQS/UQDF as the sole source of quotation data for order handling, routing, execution, and related regulatory compliance functions. That use is subject to Nasdaq's Equity 1, Section 1(a)(19), also known as the Night Session rule, which bars the session from starting until the equity data plans confirm they can collect, consolidate, process, and disseminate quote and trade information throughout it.

The change stems from the SEC's April 2026 approval of Nasdaq's 23/5 trading proposal, which created a Day Session and a Night Session, separated by a one-hour pause for maintenance and processing of corporate actions (see prior coverage). Nasdaq said the extended Night Session hours require timestamp-related changes to its market data feed handlers. The exchange chose to limit those changes to CQS/UQDF, rather than to the proprietary feeds used during the Day Session, to reduce operational risk to systems used outside the Night Session.

Nasdaq stated the amendment does not alter the existing primary and secondary source framework outside the Night Session, does not change the list of market centers, and does not affect the exchange's use of Securities Information Processor trade and administrative data.

The filing became immediately effective, though the SEC may summarily suspend the rule within 60 days of filing. Comments to the SEC are due by September 15, 2026.