The National Best Bid and Offer and How It Is Built

The NBBO is built by consolidating every exchange's best quote through the SIP, a process slower than the direct feeds firms actually trade on.

The national best bid and offer is the highest bid and lowest offer available across every registered exchange trading a security at a given instant, and it is built by a Securities Information Processor that collects each exchange's top-of-book quote and consolidates them into one published feed. That consolidation takes time to process, which means the published NBBO is always at least slightly behind what the fastest participants in the market are already seeing.

The Securities Information Processor, referred to as the SIP, receives quote and trade messages from every exchange trading a given stock and merges them into a single consolidated feed showing the best bid and offer across all venues. This feed is the regulatory NBBO, and it is what most retail brokerage platforms and slower market data consumers rely on for quotes.

Because the SIP has to receive, timestamp, and merge messages from many separate exchanges before publishing a consolidated update, it introduces processing latency that a single exchange's own direct feed does not carry.

The SIP also carries specific governance behind it, since it is operated under a national market system plan jointly overseen by the exchanges themselves rather than by a single private vendor. This structure means the SIP's technology and update cadence evolve on a slower, more consensus-driven timeline than an individual exchange's own proprietary feed.

A direct feed is a data connection from a single exchange straight to a subscriber, carrying that exchange's own quotes and trades without waiting for consolidation against any other venue. Firms with direct feeds and colocated servers see a given exchange's quote update before the SIP has finished merging it with quotes from every other exchange.