Fine-tuning market surveillance — Introducing Assisted Parameter Optimization (APO)


Danijel Grujicic – Software Engineer at Scila

In the dynamic world of financial markets, vigilance is paramount. Market surveillance teams work tirelessly to detect suspicious activities and ensure market integrity. A core tool in their arsenal? Alert rules – predefined conditions designed to flag potential misconduct, from layering to spoofing. Yet, as critical as these rules are, tuning their parameters to achieve a desired result, has long been a manual, time-consuming, and often frustrating task.

At Scila, we understand this challenge intimately. Every alert rule comes with a unique set of parameters – some discrete, like checking an option box, and some continuous, like timeframes, freely chosen numbers and imbalance ratios. Finding and defining the ‘sweet spot’ for these parameters is notoriously difficult but can be formulated as a two-part challenge. Firstly, achieving a manageable alert volume, and secondly, ensuring the quality and relevance of those alerts. This often leads to endless iterations of trial-and-error, pulling valuable time away from what analysts do best: analyzing the substance of potential market abuse.

We are pleased to present the release of our latest white paper, “Assisted Parameter Optimization (APO) for alert rules,” authored by our very own Danijel Grujicic. This paper delves into how APO can revolutionize this tedious process, bringing much-needed efficiency to market surveillance operations.

The pain point: endless tuning, limited time

Your surveillance team constantly adjusts dozens, if not hundreds, of parameters across various alert rules. Each tweak can have unpredictable effects on the alert output. Too many alerts mean analysts are drowning in noise; too few mean critical activities might be missed. The goal is to find that perfect balance, but the manual journey to get there is often slow and resource intensive.

This constant manual tuning not only impacts operational efficiency but also diverts highly skilled analysts from their core mission. Their expertise is best utilized in discerning true market abuse, not in the laborious process of system calibration.

Introducing APO: smart assistance for alert volume management

APO offers a powerful solution by tackling one crucial part of this optimization puzzle: achieving a user-defined target volume of alerts. In essence, APO systematically finds parameter values that produce the desired alert amount, providing surveillance teams with a highly efficient starting point for their analysis.

While APO, in its current form, primarily addresses the quantity of alerts, its impact is profound. By making the alert volume manageable and predictable, it empowers analysts to dedicate more focused effort to the critical task of discerning true market abuse, transforming the workflow from reactive firefighting to proactive investigation.

The science behind the efficiency: black-box optimization and evolutionary algorithms

How does APO achieve this? Danijel’s white paper explains how this challenge is contextualized as a Black-Box Optimization (BBO) problem. Think of the alert rule as a “black box” – you feed it parameters, and it outputs a number of alerts. APO’s objective is to minimize the difference between the actual alert count and your desired target.

To solve this, APO leverages Evolutionary Algorithms (EAs), a class of metaheuristic algorithms inspired by natural selection and genetic variation. These algorithms iteratively generate “populations” of potential parameter sets, evaluate their “fitness” (how close they are to the target alert volume), and then use the best-performing sets to create new, improved generations. This iterative cycle helps APO navigate complex parameter landscapes, efficiently converging towards optimal settings.

Specifically, APO utilizes the Differential Evolution (DE) algorithm, adapted to seamlessly handle the mixed-variable nature of alert rule parameters (both continuous and discrete). This sophisticated approach significantly reduces the manual workload, allowing market surveillance analysts to focus on higher-value tasks.

The impact: operational efficiency and enhanced focus

The practical results of APO are clear:

  • Reduced manual effort: Say goodbye to endless trial-and-error parameter tuning.
  • Targeted alert volume: Consistently achieve a manageable number of alerts, reducing noise.
  • Empowered analysts: Free up valuable analyst time to focus on in-depth qualitative analysis and true threat detection.
  • Innovation in surveillance: Positions your organization at the forefront of leveraging advanced optimization techniques for market integrity.

Looking ahead: the future of APO

While APO currently focuses on optimizing for alert volume, the white paper also discusses potential future developments. Imagine a future where APO incorporates analyst feedback (labeling alerts as true/false positives) to directly optimize for alert quality, maximizing true positive rates and minimizing false positives. This would further enhance its value, moving closer to direct assistance in the qualitative improvement of alert generation.