# How Does the SI Regime Impact the Measurement of Best Execution for Buy-Side Firms? ▴ Question

**Published:** 2025-08-05
**Categories:** Question

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![Two distinct components, beige and green, are securely joined by a polished blue metallic element. This embodies a high-fidelity RFQ protocol for institutional digital asset derivatives, ensuring atomic settlement and optimal liquidity](https://options.greeks.live/wp-content/uploads/2025/07/institutional-rfq-protocol-for-digital-asset-derivatives-high-fidelity-link.jpg)

## Concept

The introduction of the [Systematic Internaliser](https://prime.greeks.live/area/systematic-internaliser/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) (SI) regime under MiFID II represents a fundamental re-architecting of the European liquidity landscape. For a buy-side institution, its arrival transforms the measurement of [best execution](https://prime.greeks.live/area/best-execution/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) from a procedural compliance exercise into a complex, data-centric engineering problem. The regime provides a regulated channel for accessing principal liquidity from dealers, effectively bringing a segment of over-the-counter (OTC) activity into a more transparent framework.

An SI is an investment firm that, on an organized, frequent, systematic, and substantial basis, deals on its own account by executing client orders outside of traditional trading venues like exchanges or multilateral trading facilities (MTFs). This structure was designed to capture and illuminate bilateral trading activity, applying pre-trade transparency obligations to these flows that were previously opaque.

This development directly impacts the core logic of best execution. The mandate for buy-side firms extends beyond achieving a favorable price; it now requires a demonstrable and evidence-based justification for venue and counterparty selection across a fragmented market. The existence of SIs introduces a new, distinct category of liquidity provider that must be evaluated alongside lit markets, dark pools, and auctions. The critical challenge for a buy-side desk is that SI liquidity is not displayed in a consolidated public order book.

It is accessible primarily through bilateral request-for-quote (RFQ) protocols. Consequently, evaluating an SI’s performance requires the [buy-side firm](https://prime.greeks.live/area/buy-side-firm/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) to build or acquire a sophisticated data capture and analysis framework capable of integrating private quote data with [public market data](https://prime.greeks.live/area/public-market-data/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) to create a coherent picture of execution quality.

> The SI regime compels buy-side firms to evolve their best execution analysis from a post-trade review into a pre-trade, data-driven strategic decision process.

The core of the issue is data asymmetry. A lit market provides a continuous stream of public data against which to benchmark a trade. An SI, conversely, provides firm quotes directly to a client upon request. While the SI has a regulatory duty to report trades publicly post-execution, the buy-side firm’s ability to prove it achieved best execution hinges on its capacity to record, timestamp, and analyze every stage of that private interaction.

This includes the state of the broader market at the moment of the quote request, the speed and competitiveness of the SI’s response, and the final [execution price](https://prime.greeks.live/area/execution-price/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) relative to contemporaneous prices available on other venues. Without this internal data architecture, a firm cannot adequately defend its execution choices or systematically optimize its routing decisions.

![Abstract geometric forms converge around a central RFQ protocol engine, symbolizing institutional digital asset derivatives trading. Transparent elements represent real-time market data and algorithmic execution paths, while solid panels denote principal liquidity and robust counterparty relationships](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-core-for-high-fidelity-execution.jpg)

## How Does the SI Data Footprint Alter TCA?

Traditional [Transaction Cost Analysis](https://prime.greeks.live/area/transaction-cost-analysis/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) (TCA) models were often built around the dynamics of public order books, measuring slippage against arrival prices or volume-weighted average prices (VWAP). The SI regime complicates this analysis. The relevant benchmark for an SI execution is not just the [public market](https://prime.greeks.live/guide/why-your-best-trades-happen-off-the-public-market/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) price, but the quality of the quote itself. A buy-side firm must now answer a different set of questions ▴ Was the quote provided by the SI competitive against other SIs?

Was it better than the price available on a lit exchange at that precise moment? Did executing with the SI lead to [information leakage](https://prime.greeks.live/area/information-leakage/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite), observed through adverse price movements after the trade? Answering these questions requires a significant enhancement of TCA capabilities, moving from simple post-trade reports to a dynamic, multi-venue analytical engine.

![A translucent blue sphere is precisely centered within beige, dark, and teal channels. This depicts RFQ protocol for digital asset derivatives, enabling high-fidelity execution of a block trade within a controlled market microstructure, ensuring atomic settlement and price discovery on a Prime RFQ](https://options.greeks.live/wp-content/uploads/2025/07/precision-execution-pathway-for-institutional-digital-asset-derivatives-leveraging-rfq-protocols-and-high-fidelity-market-microstructure.jpg)

![A sleek, spherical intelligence layer component with internal blue mechanics and a precision lens. It embodies a Principal's private quotation system, driving high-fidelity execution and price discovery for digital asset derivatives through RFQ protocols, optimizing market microstructure and minimizing latency](https://options.greeks.live/wp-content/uploads/2025/08/principals-private-quotation-system-intelligence-layer-component.jpg)

## Strategy

The emergence of the SI framework necessitates a strategic recalibration for buy-side trading desks. A passive approach to execution quality measurement is insufficient. An active, strategic framework for venue and counterparty analysis must be implemented to meet the heightened best execution obligations under [MiFID II](https://prime.greeks.live/area/mifid-ii/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite).

This involves segmenting order flow based on a multi-factor analysis and directing trades to the execution channel best suited to an order’s specific characteristics, such as size, liquidity profile, and the parent order’s urgency. The decision to route an order to an SI is a strategic choice with material consequences for cost, risk, and information leakage.

A primary strategic consideration is the sourcing of liquidity for large or illiquid positions. SIs were intended, in part, to facilitate the execution of large block trades without causing significant [market impact](https://prime.greeks.live/area/market-impact/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite), a function they provide by committing their own capital. A buy-side firm’s strategy must therefore incorporate a dynamic assessment of which SIs are genuine specialists in particular asset classes or instruments.

This requires a systematic process for evaluating SI performance, moving beyond anecdotal evidence to a quantitative ranking based on historical execution data. The firm’s [Order Management System](https://prime.greeks.live/area/order-management-system/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) (OMS) and [Execution Management System](https://prime.greeks.live/area/execution-management-system/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) (EMS) become central components of this strategy, acting as the command center for implementing data-driven routing logic.

> A sophisticated buy-side strategy treats SIs not as a monolithic channel, but as a portfolio of specialized liquidity providers to be accessed based on rigorous, ongoing performance analysis.

Developing this strategy involves creating a feedback loop where post-trade analysis directly informs pre-trade decisions. The data gathered from every RFQ and execution must be fed back into the firm’s analytical models to refine its understanding of each SI’s behavior. This continuous cycle of analysis allows the [trading desk](https://prime.greeks.live/area/trading-desk/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) to build a quantitative profile of each counterparty, optimizing routing decisions to maximize [price improvement](https://prime.greeks.live/area/price-improvement/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite), minimize market impact, and control signaling risk.

![A sleek, metallic multi-lens device with glowing blue apertures symbolizes an advanced RFQ protocol engine. Its precision optics enable real-time market microstructure analysis and high-fidelity execution, facilitating automated price discovery and aggregated inquiry within a Prime RFQ](https://options.greeks.live/wp-content/uploads/2025/08/institutional-digital-asset-derivatives-rfq-engine-intelligence-layer.jpg)

## A Comparative Framework for Venue Selection

To implement a robust strategy, a buy-side firm must establish a clear, comparative framework for evaluating execution venues. This framework should weigh the distinct advantages and disadvantages of each channel against the specific objectives of a given trade. The following table provides a simplified model for such a comparison.

| Execution Venue | Primary Advantage | Primary Challenge | Optimal Use Case | Key Best Execution Metric |
| --- | --- | --- | --- | --- |
| Lit Market (e.g. Exchange) | Pre-trade price transparency | Potential for market impact on large orders | Small to medium orders in liquid instruments | Slippage vs. Arrival Price / EBBO |
| Systematic Internaliser (SI) | Access to principal liquidity; potential for price improvement | Requires robust data capture for quote analysis | Large-in-scale orders; accessing specific dealer inventory | Price Improvement vs. Contemporaneous EBBO |
| Dark Pool (e.g. MTF) | Reduced pre-trade market impact | Uncertainty of fill; potential for adverse selection | Passive, non-urgent orders seeking midpoint execution | Midpoint Price Improvement |
| Auction Mechanism | Concentrated liquidity events | Scheduled, non-continuous nature | Sourcing liquidity in less-liquid instruments | Auction Clearing Price vs. Market Price |

![A teal-blue textured sphere, signifying a unique RFQ inquiry or private quotation, precisely mounts on a metallic, institutional-grade base. Integrated into a Prime RFQ framework, it illustrates high-fidelity execution and atomic settlement for digital asset derivatives within market microstructure, ensuring capital efficiency](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-prime-os-execution-1.jpg)

## What Strategic Questions Must a Trading Desk Address?

Integrating SIs into a best execution framework requires the trading desk to develop a formal methodology for their use. This methodology should be codified in the firm’s [best execution policy](https://prime.greeks.live/area/best-execution-policy/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) and be supported by empirical data. The following questions form the basis of a sound strategic approach:

- **Counterparty Assessment** ▴ Which SIs consistently provide competitive quotes in the specific instruments we trade? This requires maintaining a performance scorecard for each SI counterparty.

- **[Routing Logic](https://prime.greeks.live/question/how-does-smart-order-routing-logic-mitigate-fragmentation-costs/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite)** ▴ Under what specific market conditions and for which order characteristics should we direct an RFQ to an SI versus another venue? This logic should be automated within the EMS where possible.

- **Information Leakage** ▴ How do we measure the market impact of our SI trades? This involves analyzing post-trade price reversion to detect signaling.

- **Data Integrity** ▴ Is our [data capture](https://prime.greeks.live/area/data-capture/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) architecture sufficient to meet regulatory scrutiny? This means recording all quote and trade data with high-precision timestamps.

- **Cost Analysis** ▴ What is the total cost of executing with an SI, including both explicit fees and implicit costs like potential opportunity cost from a rejected quote?

![Translucent teal glass pyramid and flat pane, geometrically aligned on a dark base, symbolize market microstructure and price discovery within RFQ protocols for institutional digital asset derivatives. This visualizes multi-leg spread construction, high-fidelity execution via a Principal's operational framework, ensuring atomic settlement for latent liquidity](https://options.greeks.live/wp-content/uploads/2025/07/transparent-geometric-structures-visualizing-multi-leg-spread-rfq-protocols-for-high-fidelity-institutional-digital-asset-derivatives-execution.jpg)

![Parallel execution layers, light green, interface with a dark teal curved component. This depicts a secure RFQ protocol interface for institutional digital asset derivatives, enabling price discovery and block trade execution within a Prime RFQ framework, reflecting dynamic market microstructure for high-fidelity execution](https://options.greeks.live/wp-content/uploads/2025/07/prime-os-driven-institutional-digital-asset-derivatives-rfq-execution-framework.jpg)

## Execution

The execution of a best [execution policy](https://prime.greeks.live/area/execution-policy/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) in the SI era is an operational and technological mandate. It requires the seamless integration of data analysis, system architecture, and procedural discipline. A buy-side firm must construct an operational framework that treats every trade as a data-generating event, with the ultimate goal of creating a defensible and continuously improving execution process. This moves the firm from a qualitative, relationship-based model of trading to a quantitative, evidence-based system of [execution management](https://prime.greeks.live/area/execution-management/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite).

![Precision instruments, resembling calibration tools, intersect over a central geared mechanism. This metaphor illustrates the intricate market microstructure and price discovery for institutional digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-rfq-execution-engine-microstructure-analytics.jpg)

## The Operational Playbook

Implementing a compliant and effective SI interaction model requires a detailed operational playbook. This playbook serves as a procedural guide for the entire lifecycle of an order, from the portfolio manager’s initial instruction to the final post-trade analysis. It ensures consistency, transparency, and accountability.

- **Pre-Trade Analysis and Venue Selection** ▴ 

<li>The process begins with the portfolio manager’s order entering the OMS.

- The trading desk utilizes pre-trade TCA tools to estimate the expected market impact and cost of the trade based on its size, the instrument’s liquidity profile, and current market volatility.

- Based on this analysis, the trader, guided by the firm’s routing policy embedded in the EMS, makes a preliminary decision on the optimal execution strategy. For an order deemed suitable for SI interaction (e.g. large-in-scale), the system identifies a shortlist of preferred SIs based on historical performance data.

</li>
- **RFQ Protocol Management** ▴ 

<li>The trader initiates an RFQ through the EMS, sending it either sequentially or simultaneously to the selected SIs.

- The system must log the precise timestamp of the RFQ submission and the state of the European Best Bid and Offer (EBBO) at that moment.

- As quotes are received from the SIs, the system logs each quote’s timestamp, price, and volume. The platform should present a clear, consolidated view of all responses.

</li>
- **Execution and Data Capture** ▴ 

<li>The trader executes against the chosen quote. The system records the execution timestamp, price, and volume, along with the identity of the winning SI.

- All competing quotes, including those rejected, are stored for subsequent analysis. This data is vital for evaluating the opportunity cost of the chosen execution path.

- The SI is responsible for the public trade report, which simplifies the buy-side’s reporting obligation, a key operational benefit of the regime.

</li>
- **Post-Trade Analysis and Feedback Loop** ▴ 

<li>The [execution data](https://prime.greeks.live/area/execution-data/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) is fed into the firm’s central TCA database.

- The TCA system calculates a suite of metrics for the trade, including price improvement versus the EBBO at the time of execution, slippage versus the arrival price, and post-trade price reversion over multiple time horizons (e.g. 1 minute, 5 minutes, 30 minutes).

- This analysis is aggregated to update the performance scorecards for each SI, which in turn refines the pre-trade routing logic in the EMS. This creates a closed-loop system of continuous improvement.

</li>

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## Quantitative Modeling and Data Analysis

The credibility of a buy-side firm’s best execution process rests on the quality of its quantitative analysis. The unique nature of SI interaction demands specific models and data structures. The objective is to build a composite “Execution Quality Score” (EQS) for each SI, which can be used to objectively rank and select counterparties.

> Effective quantitative modeling transforms best execution from a qualitative assessment into a measurable, optimizable engineering discipline.

The following table presents a sample of the granular data required for a robust TCA model focused on SI performance. This data must be captured for every single RFQ, not just executed trades, to provide a complete picture of an SI’s value.

| Metric | Definition | Formula / Data Source | Strategic Importance |
| --- | --- | --- | --- |
| Quote Competitiveness | The price improvement offered by the SI’s quote relative to the public market at the time the quote is received. | (SI Quote Price – Contemporaneous EBBO Midpoint) / EBBO Midpoint | Measures the direct price advantage offered by the SI. |
| Quote Response Time | The latency between the RFQ submission and the receipt of a firm quote from the SI. | (Quote Receipt Timestamp – RFQ Sent Timestamp) | Assesses the SI’s technological efficiency and market risk during the quoting interval. |
| Fill Rate | The percentage of RFQs sent to an SI that result in a successful execution with that SI. | (Number of Executed Trades with SI) / (Total RFQs Sent to SI) | Indicates the reliability and consistency of an SI’s liquidity provision. |
| Post-Trade Reversion | The movement of the market price away from the execution price after the trade, indicating potential information leakage. | (Market Midpoint at T+5min – Execution Price) / Execution Price | A critical measure of the hidden cost of a trade. High reversion suggests the trade signaled the market. |
| Composite EQS | A weighted-average score combining multiple metrics into a single performance indicator. | Weighted sum of normalized scores for competitiveness, speed, fill rate, and reversion. | Provides a unified, data-driven basis for SI selection and routing logic. |

![Two robust, intersecting structural beams, beige and teal, form an 'X' against a dark, gradient backdrop with a partial white sphere. This visualizes institutional digital asset derivatives RFQ and block trade execution, ensuring high-fidelity execution and capital efficiency through Prime RFQ FIX Protocol integration for atomic settlement](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-optimized-execution.jpg)

## Predictive Scenario Analysis

To illustrate the operational mechanics in practice, consider a hypothetical case study involving “Quantum Asset Management,” a mid-sized European long-only fund. The firm needs to execute an order to buy 500,000 shares of “Stellantis N.V.” (STLAM.MI), a reasonably liquid but still impactful order size representing approximately 15% of its average daily volume.

The portfolio manager, Dr. Aris Thorne, enters the order into Quantum’s OMS with a directive to minimize market impact and a benchmark of the day’s VWAP. The Head of Trading, Sofia Chen, is responsible for the execution strategy. Her EMS dashboard immediately flags the order as “high impact potential.” The pre-trade analytics module projects that executing the full order via a simple lit market algorithm would likely result in significant slippage against the arrival price and push the market away from the firm.

Chen’s execution policy, refined by months of TCA data, dictates a hybrid approach for orders of this nature. The policy requires splitting the order across multiple liquidity channels to diversify execution risk and reduce the overall footprint. Based on Quantum’s internal SI scorecards, two investment banks, “SI-Alpha” and “SI-Beta,” are ranked as top-tier liquidity providers for European automotive stocks.

SI-Alpha is known for its aggressive pricing but slower response times, while SI-Beta is faster but offers slightly less price improvement on average. Chen’s strategy is to engage both, alongside a passive dark pool algorithm, to create competitive tension and gather real-time market intelligence.

She configures the EMS to route 40% of the order (200,000 shares) to an RFQ process involving SI-Alpha and SI-Beta. Another 40% is allocated to a passive dark aggregation algorithm that will work the order at the midpoint. The remaining 20% is held in reserve.

At 10:00:00 AM CET, with the EBBO for STLAM.MI at €20.50 / €20.51, the EMS dispatches the RFQ for 200,000 shares. The system logs the request timestamp and the market state.

At 10:00:03 AM, SI-Beta responds with a firm quote to buy 200,000 shares at €20.508. The quote is valid for 5 seconds. Quantum’s system calculates this as a €0.003 price improvement versus the contemporaneous midpoint of €20.505. At 10:00:05 AM, SI-Alpha responds with a quote to buy 200,000 shares at €20.509, a €0.004 improvement.

Chen’s EMS automatically highlights the SI-Alpha quote as superior. She has a 2-second window to decide before the SI-Beta quote expires. She confirms the execution with SI-Alpha at 10:00:06 AM.

Simultaneously, the dark aggregator has been sourcing liquidity. Over the next hour, it executes 150,000 of its 200,000 share allocation at an average price of €20.515, primarily at the midpoint of a slowly rising market. By 11:00 AM, Chen reviews the situation. The SI execution provided significant size at a better-than-midpoint price.

The dark pool provided good execution but was slow and only partially filled. The market has now drifted to €20.52 / €20.53.

The post-trade TCA engine at Quantum gets to work that evening. It analyzes the SI-Alpha execution. The price reversion at T+5 minutes was minimal, indicating low information leakage. The price improvement was recorded and added to SI-Alpha’s scorecard, reinforcing its high rank.

The rejected quote from SI-Beta was also analyzed, providing a data point on its competitiveness under live conditions. The analysis confirms that for this specific order, the SI channel delivered superior performance for the block portion of the trade compared to what could have been achieved on other venues. This data-driven conclusion is automatically archived, providing a robust, auditable record for regulators and clients, and further refining the predictive models that will guide Sofia Chen’s decisions tomorrow.

![The abstract image features angular, parallel metallic and colored planes, suggesting structured market microstructure for digital asset derivatives. A spherical element represents a block trade or RFQ protocol inquiry, reflecting dynamic implied volatility and price discovery within a dark pool](https://options.greeks.live/wp-content/uploads/2025/07/optimized-institutional-digital-asset-derivatives-rfq-protocol-framework-ensuring-principal-best-execution-and-latent-liquidity-capture.jpg)

## How Should a Firm Architect Its Technology Stack?

A firm’s ability to execute this strategy is contingent on its technological architecture. The technology stack must be designed as an integrated system for data ingestion, analysis, and action.

- **Order & Execution Management Systems (OMS/EMS)** ▴ These are the core of the trading workflow. The EMS must have sophisticated [smart order routing](https://prime.greeks.live/area/smart-order-routing/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) (SOR) capabilities that can be customized with the firm’s proprietary SI performance data. It needs a flexible RFQ management interface that can handle simultaneous and sequential quoting protocols and integrate seamlessly with the firm’s TCA system.

- **Data Warehouse & Analytics** ▴ A centralized data repository is essential. This system must capture and store all order, quote, and execution data with high-precision (microsecond or nanosecond) timestamps. It should also ingest public market data feeds. This repository forms the foundation for all TCA and SI scoring models.

- **[FIX Protocol](https://prime.greeks.live/area/fix-protocol/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) Connectivity** ▴ Communication with SIs and other venues relies on the Financial Information eXchange (FIX) protocol. The firm’s technology team must have expertise in managing FIX connectivity and understanding the specific tags used in RFQ workflows (e.g. QuoteRequest, QuoteResponse, QuoteID).

- **TCA Provider Integration** ▴ Many firms will partner with a third-party TCA specialist. The architecture must allow for the seamless flow of data between the firm’s internal systems and the TCA provider’s platform via APIs, ensuring that the analysis is based on the firm’s complete and accurate execution data.

![Textured institutional-grade platform presents RFQ inquiry disk amidst liquidity fragmentation. Singular price discovery point floats](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-rfq-execution-microstructure-prime-os-best-execution.jpg)

## References

- Boventer, Jean-Pierre, and Ulrich Nögel. MiFID II ▴ A New Framework for European Financial Markets. Palgrave Macmillan, 2018.

- CFA Institute. Market Structure and Best Execution ▴ A Guide for Investment Professionals. 2018.

- European Securities and Markets Authority (ESMA). “MiFID II and MiFIR ▴ Report on the Development of the SI Regime.” ESMA70-156-227, 2017.

- Harris, Larry. Trading and Exchanges ▴ Market Microstructure for Practitioners. Oxford University Press, 2003.

- International Capital Market Association (ICMA). “The MiFID II/R Systematic Internaliser Regime ▴ A Summary Report.” 2017.

- Lehalle, Charles-Albert, and Sophie Laruelle, editors. Market Microstructure in Practice. World Scientific Publishing, 2013.

- Madhavan, Ananth. “Market Microstructure ▴ A Survey.” Journal of Financial Markets, vol. 3, no. 3, 2000, pp. 205-258.

- O’Hara, Maureen. Market Microstructure Theory. Blackwell Publishers, 1995.

![Polished opaque and translucent spheres intersect sharp metallic structures. This abstract composition represents advanced RFQ protocols for institutional digital asset derivatives, illustrating multi-leg spread execution, latent liquidity aggregation, and high-fidelity execution within principal-driven trading environments](https://options.greeks.live/wp-content/uploads/2025/07/digital-asset-derivatives-rfq-protocol-optimal-execution-orchestration.jpg)

## Reflection

The integration of the [Systematic Internaliser regime](https://prime.greeks.live/question/how-does-the-systematic-internaliser-regime-impact-off-venue-trade-reporting/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite) into the market’s architecture presents a profound question to every buy-side institution. It compels a shift in perspective, viewing the function of trading not as a series of discrete events, but as the management of a continuous, high-velocity data stream. The quality of a firm’s execution is now a direct reflection of the quality of its data infrastructure and its analytical intelligence.

The operational protocols and quantitative models discussed here are components of a larger system. They are the gears and levers within a firm’s execution operating system. The ultimate challenge is to ensure this system is designed for learning. A static best execution policy, however well-drafted, is a liability in a dynamic market.

A superior operational framework is one that adapts, using the output of every trade to refine its future inputs. The central question for your firm is therefore not whether you are compliant with the SI regime, but whether your operational architecture is built to generate a persistent, compounding analytical edge.

![A symmetrical, multi-faceted geometric structure, a Prime RFQ core for institutional digital asset derivatives. Its precise design embodies high-fidelity execution via RFQ protocols, enabling price discovery, liquidity aggregation, and atomic settlement within market microstructure](https://options.greeks.live/wp-content/uploads/2025/07/prime-os-institutional-digital-asset-options-rfq-engine.jpg)

## Glossary

<a href="https://prime.greeks.live/area/systematic-internaliser/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A dark blue, precision-engineered blade-like instrument, representing a digital asset derivative or multi-leg spread, rests on a light foundational block, symbolizing a private quotation or block trade. This structure intersects robust teal market infrastructure rails, indicating RFQ protocol execution within a Prime RFQ for high-fidelity execution and liquidity aggregation in institutional trading](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-execution-framework-multi-leg-spreads-best-execution-capital-efficiency.jpg)

## Systematic Internaliser

Meaning ▴ A Systematic Internaliser (SI) is a financial institution executing client orders against its own capital on an organized, frequent, systematic basis off-exchange. </a><a href="https://prime.greeks.live/area/best-execution/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A sleek, futuristic institutional grade platform with a translucent teal dome signifies a secure environment for private quotation and high-fidelity execution. A dark, reflective sphere represents an intelligence layer for algorithmic trading and price discovery within market microstructure, ensuring capital efficiency for digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/precision-rfq-execution-for-institutional-digital-asset-derivatives-1.jpg)

## Best Execution

Meaning ▴ Best Execution is the obligation to obtain the most favorable terms reasonably available for a client's order. </a><a href="https://prime.greeks.live/area/public-market-data/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Sharp, intersecting geometric planes in teal, deep blue, and beige form a precise, pointed leading edge against darkness. This signifies High-Fidelity Execution for Institutional Digital Asset Derivatives, reflecting complex Market Microstructure and Price Discovery](https://options.greeks.live/wp-content/uploads/2025/07/high-fidelity-digital-asset-derivatives-rfq-market-microstructure-2.jpg)

## Public Market Data

Meaning ▴ Public Market Data refers to the aggregate and granular information openly disseminated by trading venues and data providers, encompassing real-time and historical trade prices, executed volumes, order book depth at various price levels, and bid/ask spreads across all publicly traded digital asset instruments. </a><a href="https://prime.greeks.live/area/buy-side-firm/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Translucent and opaque geometric planes radiate from a central nexus, symbolizing layered liquidity and multi-leg spread execution via an institutional RFQ protocol. This represents high-fidelity price discovery for digital asset derivatives, showcasing optimal capital efficiency within a robust Prime RFQ framework](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-execution-engine-layer.jpg)

## Buy-Side Firm

Meaning ▴ A Buy-Side Firm functions as a primary capital allocator within the financial ecosystem, acting on behalf of institutional clients or proprietary funds to acquire and manage assets, consistently aiming to generate returns through strategic investment and trading activities across various asset classes, including institutional digital asset derivatives. </a><a href="https://prime.greeks.live/area/execution-price/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![An abstract composition featuring two overlapping digital asset liquidity pools, intersected by angular structures representing multi-leg RFQ protocols. This visualizes dynamic price discovery, high-fidelity execution, and aggregated liquidity within institutional-grade crypto derivatives OS, optimizing capital efficiency and mitigating counterparty risk](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocols-optimizing-aggregated-liquidity-and-multi-leg-execution-via-advanced-market-microstructure.jpg)

## Execution Price

Meaning ▴ The Execution Price represents the definitive, realized price at which a specific order or trade leg is completed within a financial market system. </a><a href="https://prime.greeks.live/area/transaction-cost-analysis/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Sharp, transparent, teal structures and a golden line intersect a dark void. This symbolizes market microstructure for institutional digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-precision-execution-leveraging-granular-market-microstructure-intelligence.jpg)

## Transaction Cost Analysis

Meaning ▴ Transaction Cost Analysis (TCA) is the quantitative methodology for assessing the explicit and implicit costs incurred during the execution of financial trades. </a><a href="https://prime.greeks.live/guide/why-your-best-trades-happen-off-the-public-market/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precise, multi-faceted geometric structure represents institutional digital asset derivatives RFQ protocols. Its sharp angles denote high-fidelity execution and price discovery for multi-leg spread strategies, symbolizing capital efficiency and atomic settlement within a Prime RFQ](https://options.greeks.live/wp-content/uploads/2025/07/digital-asset-derivatives-rfq-execution-microstructure-framework.jpg)

## Public Market

Access the hidden liquidity and pricing power used by top institutions to execute your best trades off the public market. </a><a href="https://prime.greeks.live/area/information-leakage/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Parallel marked channels depict granular market microstructure across diverse institutional liquidity pools. A glowing cyan ring highlights an active Request for Quote RFQ for precise price discovery](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-high-fidelity-execution-3.jpg)

## Information Leakage

Meaning ▴ Information leakage denotes the unintended or unauthorized disclosure of sensitive trading data, often concerning an institution's pending orders, strategic positions, or execution intentions, to external market participants. </a><a href="https://prime.greeks.live/area/mifid-ii/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Two intersecting metallic structures form a precise 'X', symbolizing RFQ protocols and algorithmic execution in institutional digital asset derivatives. This represents market microstructure optimization, enabling high-fidelity execution of block trades with atomic settlement for capital efficiency via a Prime RFQ](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocols-market-microstructure-execution.jpg)

## Mifid Ii

Meaning ▴ MiFID II, the Markets in Financial Instruments Directive II, constitutes a comprehensive regulatory framework enacted by the European Union to govern financial markets, investment firms, and trading venues. </a><a href="https://prime.greeks.live/area/market-impact/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Close-up reveals robust metallic components of an institutional-grade execution management system. Precision-engineered surfaces and central pivot signify high-fidelity execution for digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/institutional-grade-digital-asset-derivatives-rfq-execution-precision-optimizing-market-microstructure-for-best-execution-and-prime-os.jpg)

## Market Impact

Meaning ▴ Market Impact refers to the observed change in an asset's price resulting from the execution of a trading order, primarily influenced by the order's size relative to available liquidity and prevailing market conditions. </a><a href="https://prime.greeks.live/area/execution-management-system/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precise system balances components: an Intelligence Layer sphere on a Multi-Leg Spread bar, pivoted by a Private Quotation sphere atop a Prime RFQ dome. A Digital Asset Derivative sphere floats, embodying Implied Volatility and Dark Liquidity within Market Microstructure](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocols-high-fidelity-execution-7.jpg)

## Execution Management System

Meaning ▴ An Execution Management System (EMS) is a specialized software application engineered to facilitate and optimize the electronic execution of financial trades across diverse venues and asset classes. </a><a href="https://prime.greeks.live/area/order-management-system/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Abstract layers and metallic components depict institutional digital asset derivatives market microstructure. They symbolize multi-leg spread construction, robust FIX Protocol for high-fidelity execution, and private quotation](https://options.greeks.live/wp-content/uploads/2025/07/prime-os-digital-asset-derivatives-rfq-protocol-high-fidelity-execution.jpg)

## Order Management System

Meaning ▴ A robust Order Management System is a specialized software application engineered to oversee the complete lifecycle of financial orders, from their initial generation and routing to execution and post-trade allocation. </a><a href="https://prime.greeks.live/area/price-improvement/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precision mechanism with a central circular core and a linear element extending to a sharp tip, encased in translucent material. This symbolizes an institutional RFQ protocol's market microstructure, enabling high-fidelity execution and price discovery for digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/precision-engineered-institutional-digital-asset-derivatives-rfq-execution-engine-microstructure-facilitating-optimal-price-discovery-and-best-execution.jpg)

## Price Improvement

Meaning ▴ Price improvement denotes the execution of a trade at a more advantageous price than the prevailing National Best Bid and Offer (NBBO) at the moment of order submission. </a><a href="https://prime.greeks.live/area/trading-desk/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A polished glass sphere reflecting diagonal beige, black, and cyan bands, rests on a metallic base against a dark background. This embodies RFQ-driven Price Discovery and High-Fidelity Execution for Digital Asset Derivatives, optimizing Market Microstructure and mitigating Counterparty Risk via Prime RFQ Private Quotation](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-best-execution-protocol.jpg)

## Trading Desk

Meaning ▴ A Trading Desk represents a specialized operational system within an institutional financial entity, designed for the systematic execution, risk management, and strategic positioning of proprietary capital or client orders across various asset classes, with a particular focus on the complex and nascent digital asset derivatives landscape. </a><a href="https://prime.greeks.live/area/best-execution-policy/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precise geometric prism reflects on a dark, structured surface, symbolizing institutional digital asset derivatives market microstructure. This visualizes block trade execution and price discovery for multi-leg spreads via RFQ protocols, ensuring high-fidelity execution and capital efficiency within Prime RFQ](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocols-precision-execution.jpg)

## Best Execution Policy

Meaning ▴ The Best Execution Policy defines the obligation for a broker-dealer or trading firm to execute client orders on terms most favorable to the client. </a><a href="https://prime.greeks.live/question/how-does-smart-order-routing-logic-mitigate-fragmentation-costs/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A sleek, translucent fin-like structure emerges from a circular base against a dark background. This abstract form represents RFQ protocols and price discovery in digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-execution-protocol.jpg)

## Routing Logic

Smart Order Routing logic systematically dismantles fragmentation costs by algorithmically sourcing liquidity across disparate venues to achieve optimal price execution. </a><a href="https://prime.greeks.live/area/data-capture/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A sleek conduit, embodying an RFQ protocol and smart order routing, connects two distinct, semi-spherical liquidity pools. Its transparent core signifies an intelligence layer for algorithmic trading and high-fidelity execution of digital asset derivatives, ensuring atomic settlement](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-execution-engine-bridging-diverse-liquidity-pools-via-high-fidelity-rfq-protocol-orchestration.jpg)

## Data Capture

Meaning ▴ Data Capture refers to the precise, systematic acquisition and ingestion of raw, real-time information streams from various market sources into a structured data repository. </a><a href="https://prime.greeks.live/area/execution-management/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precise digital asset derivatives trading mechanism, featuring transparent data conduits symbolizing RFQ protocol execution and multi-leg spread strategies. Intricate gears visualize market microstructure, ensuring high-fidelity execution and robust price discovery](https://options.greeks.live/wp-content/uploads/2025/07/high-fidelity-institutional-digital-asset-derivatives-rfq-execution-framework.jpg)

## Execution Management

Meaning ▴ Execution Management defines the systematic, algorithmic orchestration of an order's lifecycle from initial submission through final fill across disparate liquidity venues within digital asset markets. </a><a href="https://prime.greeks.live/area/execution-policy/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A sophisticated RFQ engine module, its spherical lens observing market microstructure and reflecting implied volatility. This Prime RFQ component ensures high-fidelity execution for institutional digital asset derivatives, enabling private quotation for block trades](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-engine-for-best-execution-protocol.jpg)

## Execution Policy

Meaning ▴ An Execution Policy defines a structured set of rules and computational logic governing the handling and execution of financial orders within a trading system. </a><a href="https://prime.greeks.live/area/execution-data/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![Smooth, reflective, layered abstract shapes on dark background represent institutional digital asset derivatives market microstructure. This depicts RFQ protocols, facilitating liquidity aggregation, high-fidelity execution for multi-leg spreads, price discovery, and Principal's operational framework efficiency](https://options.greeks.live/wp-content/uploads/2025/08/institutional-digital-asset-derivatives-rfq-protocol-multi-leg-spreads.jpg)

## Execution Data

Meaning ▴ Execution Data comprises the comprehensive, time-stamped record of all events pertaining to an order's lifecycle within a trading system, from its initial submission to final settlement. </a><a href="https://prime.greeks.live/area/smart-order-routing/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A complex, multi-faceted crystalline object rests on a dark, reflective base against a black background. This abstract visual represents the intricate market microstructure of institutional digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-prime-os-execution-architecture.jpg)

## Smart Order Routing

Meaning ▴ Smart Order Routing is an algorithmic execution mechanism designed to identify and access optimal liquidity across disparate trading venues. </a><a href="https://prime.greeks.live/area/fix-protocol/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A conceptual image illustrates a sophisticated RFQ protocol engine, depicting the market microstructure of institutional digital asset derivatives. Two semi-spheres, one light grey and one teal, represent distinct liquidity pools or counterparties within a Prime RFQ, connected by a complex execution management system for high-fidelity execution and atomic settlement of Bitcoin options or Ethereum futures](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-market-microstructure-2.jpg)

## Fix Protocol

Meaning ▴ The Financial Information eXchange (FIX) Protocol is a global messaging standard developed specifically for the electronic communication of securities transactions and related data. </a><a href="https://prime.greeks.live/question/how-does-the-systematic-internaliser-regime-impact-off-venue-trade-reporting/?utm_source=options.greeks.live&utm_medium=referral&utm_campaign=satellite" class="glossary-item-box">
![A precise lens-like module, symbolizing high-fidelity execution and market microstructure insight, rests on a sharp blade, representing optimal smart order routing. Curved surfaces depict distinct liquidity pools within an institutional-grade Prime RFQ, enabling efficient RFQ for digital asset derivatives](https://options.greeks.live/wp-content/uploads/2025/07/high-fidelity-digital-asset-derivatives-execution-via-rfq-protocols.jpg)

## Systematic Internaliser Regime

The Systematic Internaliser regime centralizes off-venue trade reporting by making the SI solely responsible for publicizing the transaction. </a>

**Tags:** [Market Impact](https://options.greeks.live/area/market-impact/), [Buy-Side Firm](https://options.greeks.live/area/buy-side-firm/), [Systematic Internaliser](https://options.greeks.live/area/systematic-internaliser/), [Execution Policy](https://options.greeks.live/area/execution-policy/), [Request for Quote](https://options.greeks.live/area/request-for-quote/), [Execution Management System](https://options.greeks.live/area/execution-management-system/)	

## Discover More

- 
### [What Are the Primary Risks for a Buy Side Firm When Interacting with Systematic Internalisers?](https://options.greeks.live/question/what-are-the-primary-risks-for-a-buy-side-firm-when-interacting-with-systematic-internalisers/)
![A metallic blade signifies high-fidelity execution and smart order routing, piercing a complex Prime RFQ orb. Within, market microstructure, algorithmic trading, and liquidity pools are visualized. Glowing blue pathways represent RFQ protocol and price discovery, ensuring optimized capital efficiency for institutional digital asset derivatives.](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-prime-os-execution-precision.jpg)

A buy-side firm's primary risks when interacting with systematic internalisers are information leakage and adverse selection.

- 
### [What Are the Practical Steps to Implement a Compliant Options Best Execution Policy?](https://options.greeks.live/question/what-are-the-practical-steps-to-implement-a-compliant-options-best-execution-policy/)
![Interconnected translucent rings with glowing internal mechanisms symbolize an RFQ protocol engine. This Principal's Operational Framework ensures High-Fidelity Execution and precise Price Discovery for Institutional Digital Asset Derivatives, optimizing Market Microstructure and Capital Efficiency via Atomic Settlement.](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-engine-high-fidelity-execution.jpg)

A compliant options best execution policy is a dynamic, data-driven system designed to continuously optimize execution outcomes.

- 
### [How Do Regulatory Frameworks like MiFID II Influence the Use of RFQ for Best Execution?](https://options.greeks.live/question/how-do-regulatory-frameworks-like-mifid-ii-influence-the-use-of-rfq-for-best-execution/)
![A metallic, cross-shaped mechanism centrally positioned on a highly reflective, circular silicon wafer. The surrounding border reveals intricate circuit board patterns, signifying the underlying Prime RFQ and intelligence layer. This setup symbolizes high-fidelity execution within market microstructure, enabling algorithmic trading for institutional-grade digital asset derivatives and RFQ protocols with atomic settlement.](https://options.greeks.live/wp-content/uploads/2025/08/the-core-institutional-digital-asset-derivatives-rfq-os-engine-for-high-fidelity-market-microstructure.jpg)

MiFID II transforms the RFQ into a data-driven, auditable process, mandating a systematic approach to proving best execution.

- 
### [What Are the Primary Technological Challenges in Complying with MiFID II’s Best Execution Requirements?](https://options.greeks.live/question/what-are-the-primary-technological-challenges-in-complying-with-mifid-iis-best-execution-requirements/)
![A sophisticated, angular digital asset derivatives execution engine with glowing circuit traces and an integrated chip rests on a textured platform. This symbolizes advanced RFQ protocols, high-fidelity execution, and the robust Principal's operational framework supporting institutional-grade market microstructure and optimized liquidity aggregation.](https://options.greeks.live/wp-content/uploads/2025/08/advanced-digital-asset-derivatives-rfq-protocol-engine-architecture.jpg)

MiFID II best execution compliance demands an integrated data architecture to prove optimal outcomes across a vector of performance factors.

- 
### [How Has the Rise of Electronic All-To-All Platforms Changed Fixed Income Best Execution?](https://options.greeks.live/question/how-has-the-rise-of-electronic-all-to-all-platforms-changed-fixed-income-best-execution/)
![A sleek, bimodal digital asset derivatives execution interface, partially open, revealing a dark, secure internal structure. This symbolizes high-fidelity execution and strategic price discovery via institutional RFQ protocols. It optimizes capital efficiency by aggregating latent liquidity, minimizing slippage, ensuring best execution for multi-leg spreads and block trades, and mitigating information leakage.](https://options.greeks.live/wp-content/uploads/2025/08/institutional-digital-asset-derivatives-rfq-protocols-price-discovery.jpg)

All-to-all platforms rewired fixed income by creating a networked liquidity system that enhances price discovery and quantifies best execution.

- 
### [How Have Organised Trading Facilities Changed the Landscape for Fixed Income Execution Protocols?](https://options.greeks.live/question/how-have-organised-trading-facilities-changed-the-landscape-for-fixed-income-execution-protocols/)
![Transparent geometric forms symbolize high-fidelity execution and price discovery across market microstructure. A teal element signifies dynamic liquidity pools for digital asset derivatives. An opaque dome embodies principal's capital for private quotation and portfolio margin, depicting RFQ protocols on a Prime RFQ.](https://options.greeks.live/wp-content/uploads/2025/07/high-fidelity-rfq-execution-for-institutional-digital-asset-derivatives-1.jpg)

OTFs transformed fixed income by mandating electronic, transparent, and discretionary trading venues, creating a data-rich, multi-protocol ecosystem.

- 
### [What Are the Key Components of a Best Execution Policy?](https://options.greeks.live/question/what-are-the-key-components-of-a-best-execution-policy/)
![A precise, multi-faceted geometric structure represents institutional digital asset derivatives RFQ protocols. Its sharp angles denote high-fidelity execution and price discovery for multi-leg spread strategies, symbolizing capital efficiency and atomic settlement within a Prime RFQ.](https://options.greeks.live/wp-content/uploads/2025/07/digital-asset-derivatives-rfq-execution-microstructure-framework.jpg)

A Best Execution Policy is an institution's dynamic, data-driven framework for consistently delivering optimal trading outcomes.

- 
### [How Can a Firm Quantitatively Demonstrate Best Execution in a Restricted Rfq?](https://options.greeks.live/question/how-can-a-firm-quantitatively-demonstrate-best-execution-in-a-restricted-rfq/)
![A polished glass sphere reflecting diagonal beige, black, and cyan bands, rests on a metallic base against a dark background. This embodies RFQ-driven Price Discovery and High-Fidelity Execution for Digital Asset Derivatives, optimizing Market Microstructure and mitigating Counterparty Risk via Prime RFQ Private Quotation.](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-best-execution-protocol.jpg)

A firm proves best execution in a restricted RFQ by systematically benchmarking every trade against a composite of all dealer quotes.

- 
### [How Did MiFID II’s Best Execution Requirements Change Buy-Side Routing Decisions?](https://options.greeks.live/question/how-did-mifid-iis-best-execution-requirements-change-buy-side-routing-decisions/)
![Abstract geometric forms, including overlapping planes and central spherical nodes, visually represent a sophisticated institutional digital asset derivatives trading ecosystem. It depicts complex multi-leg spread execution, dynamic RFQ protocol liquidity aggregation, and high-fidelity algorithmic trading within a Prime RFQ framework, ensuring optimal price discovery and capital efficiency.](https://options.greeks.live/wp-content/uploads/2025/07/institutional-digital-asset-derivatives-rfq-protocol-liquidity-aggregation-market-microstructure-high-fidelity-execution-alpha-generation-prime-os-capital-efficiency.jpg)

MiFID II mandated a shift from qualitative best-effort to a quantitative, data-driven, and provable execution architecture.

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```


---

**Original URL:** https://options.greeks.live/question/how-does-the-si-regime-impact-the-measurement-of-best-execution-for-buy-side-firms/
