Regulation NMS (Examples)

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SUMMARY

Regulation NMS (National Market System) is a set of rules implemented by the SEC in 2005 that fundamentally transformed the structure of U.S. equity markets. These rules govern order protection, market data distribution, and market access, ensuring fair and efficient markets through mandated price protection and market linkages.

Core components of Regulation NMS

Regulation NMS consists of four primary rules that shape modern equity market structure:

Rule 611 (Order Protection Rule)

Also known as the "Trade-Through Rule," Rule 611 requires trading centers to establish policies preventing the execution of trades at prices inferior to protected quotations displayed by other trading centers. This ensures that investors receive the best available prices across all markets.

Rule 610 (Access Rule)

Establishes fair and non-discriminatory access to quotations through:

  • Limiting fees for accessing protected quotations
  • Requiring reasonable terms for linkages between markets
  • Prohibiting locked and crossed market conditions

Rule 612 (Sub-Penny Rule)

The Sub-Penny Rule prohibits markets from displaying, ranking, or accepting quotations in NMS stocks priced at 1.00ormorepershareinincrementssmallerthan1.00 or more per share in increments smaller than 0.01. This prevents excessive quote flickering and maintains orderly markets.

Rule 603 (Market Data Rule)

Rule 603 establishes requirements for distributing market data:

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Impact on market structure

Regulation NMS has profoundly influenced modern market structure through:

Market fragmentation

The regulation has led to increased market fragmentation, creating:

  • Multiple competing exchanges
  • Alternative Trading Systems (ATSs)
  • Dark pools

Technology requirements

Implementation demands sophisticated technology:

Order types and routing

The rules have spawned numerous specialized order types:

Market data implications

Regulation NMS has significant implications for market data:

Data hierarchy

  • Protected quotations must be immediately accessible
  • Real-Time Market Data (RTMD) distribution requirements
  • Mandated consolidated tape reporting

Latency considerations

Compliance requirements

Market participants must maintain:

Modern challenges

Current market structure debates center on:

  • Market data latency differentials
  • Exchange pricing models
  • Technology requirements for compliance
  • Competition between exchanges and ATSs

Regulation NMS continues to evolve with market structure changes, technological advances, and new trading practices, requiring ongoing adaptation by market participants and infrastructure providers.

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