Forging Financial Futures: Synthetic Data for a New Era

Author: Denis Avetisyan


Researchers have developed a new framework for creating realistic and privacy-preserving financial transaction data, unlocking opportunities for innovation and analysis.

PersonaLedger establishes a dataset linking defined user personas to detailed sequences of transactional and payment activity, providing a foundation for analyzing behavioral patterns through financial interactions.
PersonaLedger establishes a dataset linking defined user personas to detailed sequences of transactional and payment activity, providing a foundation for analyzing behavioral patterns through financial interactions.

PersonaLedger combines Large Language Models with rule-based systems to generate high-fidelity synthetic time series data for financial applications.

Access to real-world financial transaction data is severely restricted by privacy regulations, hindering open research in financial AI. To address this, we introduce PersonaLedger: Generating Realistic Financial Transactions with Persona Conditioned LLMs and Rule Grounded Feedback, a novel framework that combines large language models with a rule-based engine to generate high-fidelity, privacy-preserving synthetic data. This approach yields realistic transaction streams grounded in both behavioral diversity and financial correctness, demonstrated through a public dataset of 30 million transactions. Will this new resource accelerate innovation in forecasting and anomaly detection, enabling more robust and reproducible financial AI research?


Deconstructing Financial Reality: The Data Illusion

Current financial datasets frequently present a simplified view of real-world transactions, posing a challenge to the development of effective fraud detection and risk assessment models. These datasets often lack the nuanced patterns, intricate correlations, and inherent irregularities present in genuine financial activity; they tend to be heavily curated, standardized, and focused on a limited set of transaction types. This simplification can lead to models that perform well on benchmark tests but struggle when deployed in live environments facing diverse and evolving fraud schemes. Consequently, models trained on such data may exhibit low recall – failing to identify genuine fraudulent activity – or high false positive rates, unnecessarily flagging legitimate transactions as suspicious. The limited complexity hinders a model’s ability to generalize to unseen data, reducing its overall robustness and practical utility in a dynamic financial landscape.

Existing public financial datasets frequently present a skewed or outdated representation of actual spending behaviors and fraudulent activities, ultimately limiting the effectiveness of predictive models. These datasets, often compiled from historical records, struggle to capture the dynamic nature of financial transactions, failing to reflect contemporary purchasing trends, the rise of digital currencies, or the increasingly sophisticated methods employed by fraudsters. Consequently, models trained on such data may exhibit poor generalization performance when deployed in real-world scenarios, misclassifying legitimate transactions as fraudulent or, more critically, failing to detect novel fraud schemes. The inability to accurately mirror current financial landscapes poses a substantial challenge to developing robust and reliable systems for fraud detection and risk assessment, necessitating innovative approaches to data acquisition and model training.

The development of effective fraud detection systems and accurate risk assessment tools is increasingly hampered by restrictions on accessing genuine financial transaction data. Strict privacy regulations, such as GDPR and CCPA, alongside growing consumer awareness and concerns regarding data security, have created significant barriers for researchers and developers. While these protections are vital, they inadvertently limit the availability of the large, diverse datasets needed to train and validate complex machine learning models. Consequently, innovation is stifled, and the ability to proactively address evolving financial threats is diminished, as models trained on limited or outdated data may struggle to generalize to real-world scenarios and accurately identify novel fraud patterns. This challenge necessitates the exploration of alternative approaches, including advanced data anonymization techniques and the generation of synthetic datasets that preserve statistical properties without compromising individual privacy.

The limitations surrounding access to genuine financial data are driving a critical need for scalable synthetic data generation. Current fraud detection and risk assessment systems require extensive, evolving datasets for effective training, yet privacy regulations and data security concerns frequently impede research and development. A viable solution lies in the creation of artificial datasets that accurately mimic the statistical properties and complexities of real-world transactions – including irregular patterns indicative of fraudulent activity. Such a system must be capable of producing vast quantities of data, adaptable to changing financial landscapes, and robust enough to avoid introducing biases that could compromise model performance. Ultimately, a scalable synthetic data solution promises to unlock innovation in financial technology while upholding crucial data protection principles.

A naive prompting baseline using Llama-3.3-70B resulted in unrealistic transactions, as demonstrated in this case study.
A naive prompting baseline using Llama-3.3-70B resulted in unrealistic transactions, as demonstrated in this case study.

PersonaLedger: Forging Reality from Algorithms

PersonaLedger generates synthetic transaction data by integrating Large Language Models (LLMs) and programmatic controls. LLMs are utilized to propose transactions, leveraging their ability to create varied and plausible data points. However, to ensure the generated data adheres to established financial principles and maintains internal consistency, a Programmatic Controller is implemented. This controller enforces pre-defined rules and constraints, validating each proposed transaction before it is added to the dataset. The combination of LLM-driven creativity and programmatic validation allows PersonaLedger to produce both diverse and reliable synthetic financial data.

PersonaLedger utilizes detailed User Personas as the foundation for generating synthetic financial data. These personas are constructed using resources such as Nemotron-Personas, which provide comprehensive demographic, behavioral, and financial attributes. Each persona includes information pertaining to income, employment status, age, location, and spending habits. This detailed profiling allows the system to simulate realistic financial behaviors, including varying transaction frequencies, amounts, and categories, tailored to the specific characteristics of each persona. The granularity of these profiles extends to include preferences for merchants, payment methods, and typical monthly expenses, ensuring the generated data reflects diverse and plausible consumer financial profiles.

The data generation process within PersonaLedger utilizes Large Language Models (LLMs) to initially propose individual transactions, informed by the established user personas and their associated financial behaviors. These proposed transactions are then subject to validation and correction by a Programmatic Controller. This controller enforces predefined Accounting Invariants – rules governing the fundamental principles of accounting, such as the balance of debits and credits – to guarantee the synthetic dataset maintains financial consistency. Specifically, the controller verifies that each transaction adheres to these invariants, adjusting or rejecting proposals that violate them, thereby ensuring the overall dataset’s integrity and usability for downstream financial applications and analysis.

The combination of LLM-driven transaction proposal and programmatic accounting rule enforcement facilitates the generation of synthetic datasets applicable to multiple financial use cases. These datasets support applications including fraud detection model training, anti-money laundering (AML) system testing, credit risk assessment, and the development of personalized financial products. The diversity of generated data is achieved through variations in User Persona characteristics and LLM stochasticity, while the enforcement of Accounting Invariants – such as debit/credit balance and transaction legality – guarantees the data’s financial validity and usability for sensitive applications requiring precise record-keeping.

The demonstrated system leverages large language model reasoning about a trajectory plan to generate strongly-constrained personas and transactions.
The demonstrated system leverages large language model reasoning about a trajectory plan to generate strongly-constrained personas and transactions.

Reconstructing Transactions: A Methodology of Validation

PersonaLedger employs a hybrid transaction generation strategy, combining rule-based systems with Generative Adversarial Networks (GANs). Rule-based generation establishes a foundational dataset through predefined logic and parameters, providing a controlled and predictable baseline for system behavior. GANs, conversely, introduce a higher degree of complexity and realism by learning patterns from existing financial data and generating novel transactions that mimic these patterns. This approach allows for the creation of more diverse and statistically representative transaction histories compared to solely relying on deterministic rule-based methods, ultimately enhancing the fidelity of simulated user financial profiles.

The Large Language Model (LLM) within PersonaLedger generates Transaction Proposals that detail the specifics of a potential financial event. These proposals are constructed by referencing the individual User Financial Profile, which contains data on established spending habits and financial characteristics. Each proposal includes three key elements: the transaction amount, the merchant associated with the transaction, and the type of transaction-for example, purchase, bill payment, or transfer. The LLM uses this profile data to create realistic transaction scenarios, forming the basis for simulated financial activity within the system.

The Programmatic Controller operates as a critical safeguard within the transaction processing pipeline, performing validation checks against predefined Accounting Invariants prior to any State Update. These invariants encompass rules governing balance adjustments – ensuring debits and credits remain equal – and payment validity, which confirms sufficient funds are available for each transaction. Validation includes verifying that transaction amounts are non-negative, that account balances do not fall below permitted thresholds, and that all postings adhere to established accounting principles. Successful validation is a prerequisite for the State Update, which permanently records the transaction and modifies relevant account balances; failed validation results in transaction rejection and logging of the error for auditability and system maintenance.

A dataset of 30 million financial transactions was programmatically generated, representing the activity of 23,000 unique users. This scale of data allows for statistically significant analysis of complex financial behaviors and variables. Specifically, the dataset facilitates nuanced examination of metrics such as Credit Utilization Rate, providing insights into user spending patterns and credit health. Furthermore, the inclusion of variable recurring bills – categorized as ‘Variable Bill’ within the dataset – enables research into irregular payment schedules and their impact on financial forecasting and risk assessment. The generated data supports the evaluation and refinement of financial models and algorithms.

This iterative pipeline leverages a stateful program to enforce accounting rules, prompting a large language model to generate daily plans and update the system’s state for subsequent cycles.
This iterative pipeline leverages a stateful program to enforce accounting rules, prompting a large language model to generate daily plans and update the system’s state for subsequent cycles.

The Ripple Effect: Synthetic Data and the Future of Finance

PersonaLedger’s synthetic transaction data is proving instrumental in bolstering fraud detection capabilities, particularly within the complex domain of identity theft segmentation. By generating realistic, yet anonymized, financial interactions, the system allows developers to train and rigorously validate fraud models without encountering the limitations and risks associated with genuine customer data. This approach enables the creation of more accurate algorithms capable of discerning fraudulent activity and correctly identifying instances of identity theft, even in the face of evolving tactics. The availability of controlled, labeled synthetic data accelerates model development cycles and allows for comprehensive testing under a variety of simulated conditions, ultimately leading to more robust and reliable fraud prevention systems.

PersonaLedger’s synthetic transaction data demonstrably enhances the creation of resilient models for both credit risk assessment and illiquidity classification. Rigorous testing reveals that models trained on this data achieve measurable performance improvements when evaluated against established benchmark tasks; specifically, the synthetic data enables more accurate identification of individuals likely to default on loans or face financial distress. This enhanced predictive capability stems from the ability to generate diverse and representative datasets, effectively addressing the limitations of relying solely on scarce or biased real-world financial information. Consequently, financial institutions and researchers can build more reliable and equitable risk assessment tools, leading to improved financial stability and responsible lending practices.

PersonaLedger addresses a critical bottleneck in financial innovation by enabling access to data previously locked behind stringent privacy regulations. Traditional financial datasets, rich with insights into consumer behavior and market trends, are often inaccessible to researchers and developers due to concerns over personally identifiable information. This system circumvents those limitations by generating synthetic data – statistically representative datasets that mirror the characteristics of real financial transactions without containing actual individual data. Consequently, PersonaLedger democratizes financial data access, fostering broader participation in research and development, particularly for smaller institutions and independent researchers who may lack the resources to navigate complex data acquisition processes and compliance requirements. This broadened access promises accelerated innovation in areas like fraud detection, risk assessment, and financial inclusion, all while upholding robust privacy standards.

Ongoing development focuses on refining PersonaLedger’s data generation capabilities through the incorporation of increasingly nuanced behavioral models. Current efforts aim to move beyond static simulations towards systems that learn and adapt, mirroring the evolving patterns of real-world financial transactions. This includes exploring techniques like generative adversarial networks and reinforcement learning to create synthetic datasets that more accurately reflect complex user behaviors and emerging fraud schemes. Ultimately, the goal is to create adaptive data generation-where the synthetic data dynamically adjusts to reflect changes in the underlying population and proactively addresses potential vulnerabilities in fraud detection and risk assessment systems, ensuring continued effectiveness and resilience.

Average monthly spending varies significantly across different persona attributes, as indicated by the error bars representing data dispersion.
Average monthly spending varies significantly across different persona attributes, as indicated by the error bars representing data dispersion.

The framework detailed in PersonaLedger operates on a principle of controlled deviation. It isn’t merely about creating data, but about intelligently challenging the boundaries of what constitutes a ‘realistic’ financial transaction. This resonates with the sentiment expressed by Blaise Pascal: “The eloquence of angels is no more than the silence of reason.” Just as Pascal suggests a deeper understanding lies beyond surface expression, PersonaLedger doesn’t simply mimic existing data patterns. Instead, it utilizes rule-grounded feedback to probe and refine its generative process, exposing the underlying logic governing financial behavior. The system actively ‘tests’ the rules, pushing against the constraints to achieve a higher fidelity in its synthetic data generation, similar to reverse-engineering a complex system to truly comprehend it. This approach ensures the generated transactions aren’t just plausible, but grounded in an understanding of the fundamental principles at play.

What Lies Beneath?

PersonaLedger, in its attempt to simulate the chaotic dance of financial transactions, necessarily highlights what simulation cannot fully capture. The framework skillfully navigates the tension between generating realistic data and upholding privacy, but it skirts the fundamental question: is perfect anonymization even possible when behavioral patterns are, by definition, identifiable? The rule-grounded feedback loop is a clever constraint, but constraints, like any boundary, invite inventive circumvention. Future iterations might benefit from actively introducing controlled breaches of these rules, observing how the system adapts – a kind of adversarial training for synthetic data itself.

The current emphasis on time-series fidelity is laudable, yet financial systems aren’t merely sequences of events; they are complex adaptive networks. The next step isn’t simply longer simulations, but models that incorporate agent-based interactions – artificial actors with evolving motivations and unpredictable responses. Can a synthetic financial world, populated by these digital entities, reveal systemic vulnerabilities currently hidden within the real one? Perhaps the most valuable data generated won’t be accurate replicas of transactions, but entirely novel failure modes.

Ultimately, the pursuit of perfect synthetic data is a fool’s errand. Reality is messy, illogical, and frequently self-contradictory. The true challenge isn’t mimicking the surface, but reverse-engineering the underlying principles – the hidden algorithms that govern economic behavior. PersonaLedger isn’t the destination; it’s a particularly well-equipped disassembly kit.


Original article: https://arxiv.org/pdf/2601.03149.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/

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2026-01-07 19:04