Engineered Simultaneity: The Physical Impossibility of Consolidated Price Discovery Across Spacelike-Separated Exchanges

A groundbreaking paper by computer scientist Paul Borrill, 'Engineered Simultaneity: The Physical Impossibility of Consolidated Price Discovery Across Spacelike-Separated Exchanges,' applies principles from Einstein's theory of relativity to expose a fundamental flaw in US financial market regulation. The research demonstrates that the Securities and Exchange Commission's Regulation NMS Rule 611, which mandates a consolidated National Best Bid and Offer (NBBO), requires comparing prices at exchanges separated by 43 to 1,180 kilometers. Because information cannot travel faster than light, this creates an unavoidable 143 to 3,940 microsecond window during which no single, objective 'current' price exists across all exchanges—the NBBO's value literally depends on an observer's reference frame. Borrill argues this constitutes a 'category mistake,' applying the concept of simultaneity where it has no frame-independent meaning.

This theoretical impossibility has a massive, quantifiable real-world impact. High-frequency trading (HFT) firms exploit this window by subscribing to proprietary direct data feeds from exchanges, which have latencies in the tens of microseconds. Meanwhile, the official consolidated Securities Information Processor (SIP) that calculates the NBBO for the public operates at about 1,128 microseconds—a latency disadvantage exceeding 50:1. This creates a persistent information asymmetry where HFTs can act on faster price data before the official NBBO updates, allowing them to engage in latency arbitrage. Borrill calculates this structural advantage extracts approximately $5 billion annually from other market participants, including retail investors and traditional institutions. The paper forces a reckoning for regulators, suggesting that market rules built on the physically impossible concept of instantaneous, consolidated price discovery require a fundamental redesign.