What is NBBO?

The National Best Bid and Offer (NBBO) is a critical financial benchmark in the trading world that reflects the highest bid price and lowest ask price for a security, drawn from all available exchanges and trading venues. This information represents the tightest composite bid-ask spread available in the market, ensuring that both buyers and sellers have access to the best potential prices when executing trades.

Regulatory Backing: Regulation NMS

Enforced by the Securities and Exchange Commission (SEC) under Regulation National Market System (NMS), brokers are required to execute trades at the best available ask and bid prices. This regulation ensures fairness and optimal pricing, providing investors with the quote at the time of trade based on the NBBO. Thus, the NBBO not only serves as a pricing benchmark but also ensures that investors, including retail traders, receive competitive prices without actively needing to seek out the best offers across various platforms.

How is the NBBO Calculated?

The NBBO is calculated and disseminated by Security Information Processors (SIPs), which process pricing data as part of the National Market System Plan (NMSP). There are two main SIPs managing this data:

The NBBO is updated throughout the trading day, ensuring that the displayed bid and ask prices reflect the current market activity. It is important to note that the lowest ask price and the highest bid price do not necessarily come from the same exchange; if they do, the term "best bid and offer" is used instead of "NBBO."

Limitations of the NBBO

While the NBBO aims to provide the best available price, it is often not a real-time reflection of market data. Trades executed based on the NBBO may sometimes differ from a trader's price expectations. For example, dark pools and other alternative trading systems, known for their less transparent operations, might not be represented in NBBO calculations, which can further complicate price accuracy.

Advantages of NBBO

The implementation of the NBBO has several benefits:

Disadvantages of NBBO

Despite its advantages, the NBBO also has some drawbacks:

NBBO and High-Frequency Trading (HFT)

High-frequency trading firms invest significantly in advanced technological infrastructure that allows them to connect directly to exchanges. Their operational advantage enables them to process orders faster than traditional brokerages. In this light, HFTs may bypass NBBO data and capitalize on discrepancies before they are reflected in public price quotes.

Research, such as a 2013 University of Michigan study, examined the profitability of trading strategies that exploit the latency between the publication of the NBBO and its underlying trades. The study indicated that as much as $21 billion could be profited by HFTs utilizing these tactics.

Example of NBBO Calculation

To illustrate the concept of NBBO, consider the following scenario involving company ABC:

From these values, the NBBO for company ABC would be $950/$1,000, indicating that the highest bid available was $950 and the lowest ask was $1,000.

Conclusion

The National Best Bid and Offer plays a fundamental role in ensuring efficient and fair trading within the securities market. While it provides valuable insights into market dynamics and helps protect investors, users should remain aware of its limitations, especially in high-frequency trading environments. Understanding NBBO is essential for any trader or investor looking to navigate the complexities of the financial markets effectively.