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NBBO — the National Best Bid and Offer — is a quote available marketwide that represents the tightest composite spread for a security, e.g., the highest bid price and the lowest ask price for that security trading on various exchanges.
The NBBO is a regulation put in place by the Securities and Exchange Commission (SEC) that requires brokers who are working on behalf of clients to execute a trade at the best available ask price, and the best available bid price.
Brokers must guarantee at least the NBBO to their clients at the time of a trade, per SEC rules.
Key Points
• The National Best Bid and Offer (NBBO) is a marketwide quote for the highest bid price and the lowest ask price for a security across exchanges.
• The SEC enacted the NBBO regulation to ensure brokers execute trades for clients at the best available bid and ask prices (the bid-ask spread).
• The bid-ask spread is the difference between the price an investor is willing to buy (bid) and the price a seller is willing to sell (ask).
• Securities Information Processors (SIPs) continuously process bid and ask prices to calculate and update the NBBO.
• There can be a slight lag in real-time data due to the high volume of transactions, which the SEC addresses with intermarket sweep orders (ISO).
How Does “Bid vs Ask” Work in the Stock Market
In order to understand NBBO, investors need to understand the bid-ask price of a security, such as a stock. This is also known as the spread (two of many terms investors and traders should know). If an investor is “bidding,” they’re looking to buy. If they’re “asking,” they’re looking to sell. It may be helpful to think of it in terms of an “asking price,” as seen in real estate.
The average investor or trader will typically see the bid or ask price when looking at prices for different securities. Most of the bid-ask action takes place behind the scenes, and it’s happening fast, landing on an average price. These are the prices represented by stock quotes.
That price is the value at which brokers or traders are required to guarantee to their customers when executing orders. NBBO requires brokers to act in the best interest of their clients.
Recommended: How to Invest in Stocks: A Beginner’s Guide
What Is NBBO?
The National Best Bid and Offer (NBBO) is effectively a consolidated quote of the highest available bid and the lowest available ask price of a security across all exchanges. NBBO was created by the SEC to help ensure that brokers offer customers the best publicly available bid and ask prices when investors buy stocks online or through a traditional brokerage.
NBBO Example
Let’s run through a quick example of how the NBBO might work in the real world.
Let’s suppose that a broker has a few clients that want to buy stock:
• Buyer 1 puts in an order to the broker to buy shares of Company X at $10
• Buyer 2 puts in an order to the broker to buy shares of Company X at $10.50
• Buyer 3 puts in an order to the broker to buy shares of Company X at $11
Remember, these are “bids” — the price at which each client is willing to purchase a share of Company X.
On the other side of the equation, we have another broker with two clients that want to sell their shares of Company X, but only if the price reaches a certain level:
• Client 1 wants to sell their shares of Company X if the price hits $12
• Client 2 wants to sell their shares of Company X if the price hits $14
In this example, the NBBO for Company X is $11/$12. Why? Because these are the best bid vs. ask prices that were available to the brokers at the time. This is, on a very basic level, how calculating the NBBO for a given security might work.
Recommended: Stock Trading Basics
How NBBO and “Bid vs Ask” Prices Are Calculated
Because the NBBO is updated constantly through the day with offers for stocks from a number of exchanges and market players, things need to move fast.
Most of the heavy lifting in NBBO calculations is done by Securities Information Processors (SIPs). SIPs connect the markets, processing bid and ask prices and trades into a single data feed. They were created by the SEC as a part of the Regulation National Market System (NMS).
There are two SIPS in the U.S.: The Consolidated Tape Association (CTA) , which works with the New York Stock Exchange, and the Unlisted Trading Privileges (UTP) , which works with stocks listed on the Nasdaq exchange.
The SIPS crunch all of the numbers and data to keep prices (NBBO) updated throughout the day. They’re incredibly important for traders, investors, brokers, and anyone else working in or adjacent to the markets.
Is NBBO Pricing Up to Date?
The NBBO system may not reflect the most up-to-date pricing data. Bid, ask, and transaction data is changing every millisecond. For high-frequency traders that are making fast and furious moves on the market, these small price fluctuations can cost them.
To make up for this lag time, the SEC allows trading via intermarket sweep orders (ISO), letting an investor send orders to multiple exchanges in order to execute a trade, regardless of whether a price is the best nationwide.
The Takeaway
NBBO represents the crunching of the numbers between the bid-ask spread of a security, and it’s the price you’ll see listed on a financial news network or stock quote.
The NBBO adds some legal protection for investors, effectively forcing brokers to execute trades at the best possible price for their clients.
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FAQ
What does NBBO mean in trading?
The National Best Bid and Offer (NBBO) is a marketwide quote for the highest bid price and the lowest ask price available for a security, across exchanges. That means it’s a composite or consolidated quote that ensures investors are getting the best available price for a security.
What is Level 2?
Level 2 is a subscription-based service offered by Nasdaq that gives traders access to live trading data from the exchange, including bid-ask spreads and order sizes from market makers. Level 2 offers more in-depth information about pricing than NBBO, which is part of a Level 1 trading screen.
What is the advantage of NBBO?
First and foremost, NBBO helps protect investors, by ensuring the tightest spreads for securities prices. As such, NBBO also promotes market transparency and competition.
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