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Order Protection Rule


The Order Protection Rule, also known as Rule 611, is a part of the Regulation National Market System (NMS) in the United States. It requires trading centers to prevent “trade-throughs” , which are trades executed at prices that are inferior to displayed quotes at other trading centers. The goal is to ensure investors get the best possible price when buying or selling stocks.


The phonetics for the keyword: Order Protection Rule is -Order: /ˈɔːdər/Protection: /prəˈtɛkʃən/Rule: /ruːl/

Key Takeaways

  1. The Order Protection Rule (OPR) is part of the Regulation National Market System (NMS) which aims to ensure layers of investor protection, fostering both market and price competition. It largely serves to prevent trade-throughs, or the execution of trades at prices worse than the best quoted prices.
  2. OPR requires that trading centers (which includes national securities exchanges and dealers) establish, maintain, and enforce written policies and procedures reasonably schemed to prevent the execution of trades at prices that are inferior to the protected quotations displayed by other trading centers, except when such trade-through is permitted.
  3. Overall, the intent of the OPR is to maintain a fair and efficient market system, offering paramount protection to investors by ensuring they receive the best execution price for their trade, regardless of which exchange the trade gets executed.


The Order Protection Rule, also known as Rule 611 under the Regulation National Market System (Reg NMS), is significant in business because it helps ensure that investors receive the best possible price when trading stocks. This rule requires all trading centers to prevent trade-throughs, transactions executed at prices worse than the best available price in the market. This not only guarantees fair pricing, but it also encourages competition among exchanges, thereby improving market efficiency. Investors and brokers are thus confident that they are getting the maximum possible profit from their transactions, contributing to an overall healthier and more trustworthy investment environment.


The Order Protection Rule, also known as Rule 611, was established to foster fair and orderly markets with the intent to prevent trade-throughs. A trade through is when a trade is executed on one exchange when a better price is available on another exchange. The Order Protection Rule is designed to guard investors from getting their trades executed at prices worse than the prices available from a different trading center. By preventing trade-throughs, the rule ensures that investors get the best price irrespective of where their orders are placed, thus promoting competition among different marketplaces and increasing overall market quality.The Order Protection Rule also plays an integral role in maintaining the efficient functioning of the National Market System. It ensures that all domestic trading venues are connected electronically, allowing buyers and sellers to meet with the most competitive prices across all platforms. In the modern electronic trading environment where fractions of a second can mean the difference between profits and losses, the Order Protection Rule ensures that all displayed trading interests are protected. This enhances the market transparency, investor confidence, and leaves little room for manipulation and unfair trading practices.


The Order Protection Rule, also known as Rule 611, is part of Regulation NMS (National Market System). This rule is implemented by the Securities and Exchange Commission (SEC) and it ensures that investors receive an execution price that is equivalent to the best displayed price on any of the US’s trading venues. The rule is designed to prevent trade-throughs – the execution of trades at prices worse than the best available price without a valid exception.Real World Example 1: Brokerages & Stock OrdersWhen an investor places an order to buy a stock through a brokerage, the Order Protection Rule ensures the investor gets the best price. If the best price is available on a different trading venue to where the brokerage usually operates, the rule forces the brokerage to route the order to the venue with the best price to comply with the rule.Real World Example 2: Trading Platforms & Accurate Pricing Common trading platforms or stock exchanges like Nasdaq or the New York Stock Exchange (NYSE) are also subject to the Order Protection Rule. These platforms must display the most accurate pricing information so that investors can trust they’re getting the best possible price for a trade. They also need to ensure they are connected to other exchanges so they can send orders to these exchanges if they have a better price.Real World Example 3: Handling Mistakes There could be instances where a mistake or error occurs, and a trade is executed at a price that’s worse than the best price available. The Order Protection Rule requires the broker or dealer to rectify the situation by providing the investor with price adjustment so that they receive the equivalent to the best price at the time of their order. This upholds investor’s trust and transparency in trading systems.

Frequently Asked Questions(FAQ)

What is the Order Protection Rule?

The Order Protection Rule, also known as Rule 611, is a policy under the Regulation National Market System (Reg. NMS) by the Securities and Exchange Commission. The rule is meant to ensure that investors receive an execution price at least as good as the best displayed market quote across all U.S. exchanges.

When was the Order Protection Rule implemented?

The Order Protection Rule was implemented by the SEC as part of the Regulation NMS, which was approved in 2005 and implemented fully by 2007.

Why was the Order Protection Rule created?

The Order Protection Rule was created to prevent trade-throughs – executing a trade at a price other than the best available price across all exchanges. The rule aims to encourage competition among market centers, leading to better order executions.

How does the Order Protection Rule benefit investors?

Under the Order Protection Rule, traders are required to route orders to the exchange offering the best price at that time. This ensures investors get the best possible deal for their transactions, promoting market transparency and fairness.

How does the Order Protection Rule apply to stock trades?

For stock trades, the Order Protection Rule ensures that any order must be executed at a price that is at least as good as the national best bid or offer (NBBO). The NBBO represents the highest bid and the lowest offer for a stock among all exchanges and trading platforms.

Are there any criticisms of the Order Protection Rule?

Yes, some critics argue that the Order Protection Rule can lead to increased complexity and cost within the trading system. Despite this, its proponents maintain that it levels the playing field for investors and improves market efficiency.

Can the Order Protection Rule be waived or overridden?

Generally, the Order Protection Rule is strictly enforced. However, there are some exceptions, such as when a trade is deemed to be of de minimis size or the price difference is not substantial for certain securities.

How does the Order Protection Rule affect brokerage firms?

Brokerage firms must comply with the Order Protection Rule. This means they need sophisticated systems to determine the best market for each order, ensuring they don’t trade-through better priced quotes and making sure their customers get the best possible deal on their trades.

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