The Ipso Facto Team
Dr. William Segal, CFA
William Segal is founder and Managing Director at Ipso Facto Solutions, offering financial model development, risk management, and audit services.
With more than 30 years of industry, academic, and regulatory experience at firms including Fannie Mae and Capital One, as well as federal financial regulatory agencies, he has developed and validated a variety of models including machine learning, commercial and retail credit risk, fixed income market risk, counterparty risk, and financial crime risk.
His principal value-add is in the areas of team leadership, project management, senior management communication, and regulatory strategy. Dr. Segal holds a BA from Harvard and a PhD from Berkeley.
Stefan Szilagyi, Managing Director
Stefan Szilagyi is a results-driven professional with extensive experience in financial services and regulatory agencies with expertise in market risk, model development, capital markets, model validations, financial modeling, CCAR and DFAST, credit risk, operational risk, and climate change modeling.
As the Examinations Manager for Risk Modeling at the Federal Housing Finance Agency, he led the implementation of Dodd-Frank Act Stress Testing requirements and spearheaded the agency-wide effort to assess exposure to climate change. With extensive experience in overseeing model risk examinations, interest rate risk modeling, and performance evaluations, he has a strong background in managing complex risk modeling projects and producing comprehensive market risk reports.
Previously, Stefan held positions such as Principal Economist at the Federal Housing Finance Agency, Director of Valuation and Risk Metrics Control at Freddie Mac, and Senior Financial Specialist at FISERV - IPS-Sendero. In these roles, he developed risk management systems, optimized funding and hedging strategies, and led operational risk management initiatives.
Stefan has demonstrated significant industry leadership through extensive research and numerous speaking engagements. At the forefront of model risk management, he has presented at prestigious conferences such as the Model Risk Conference in New York and San Francisco, discussing topics ranging from the impact of AI and ML on SR 11-7 to contrasting model risk with model uncertainty. he has also shared insights on optimizing DFAST strategies, negative interest rates in the context of Dodd-Frank stress testing, and enhancing dialogue between regulators and the industry.
In addition to these conferences, he has led training courses and workshops at the Federal Housing Finance Agency, focusing on stress testing, capital impact, and model risk management. He has also contributed to the FHLBank Market Risk Managers' Conferences, addressing model validation and market risk at the Federal Home Loan Banks. Through these engagements, he has established a reputation as a thought leader in the field, driving forward the understanding and implementation of effective risk management practices.
Stefan holds a Master's in Financial Economics and is a member of the Global Association of Risk Professionals (GARP). He has published several articles on risk management and financial modeling.
Judy Zhu
Jiayi (Judy) Zhu is a Risk Modeling and Data Analyst at Ipso Facto Solutions, where she supports analytical and advisory work across financial modeling, data analytics, and risk management. Her experience spans investment banking and quantitative finance, with exposure to large-scale financial data processing and model-driven decision support. She is proficient in programming, particularly in Python, R, and SQL, with strong expertise in statistical analysis and time-series modeling applied to financial risk analytics.
Judy holds dual Bachelor’s degrees in Statistics and Economics from the University of California, San Diego, and is currently pursuing a Master’s degree in Financial Engineering at New York University.
Isaac Segal,
CISO
Isaac Segal is Chief Information Security Officer at Ipso Facto Solutions, offering experience with systems administration, IT solutions, and cybersecurity.
Isaac is a certified AWS Cloud Practitioner, and has extensive experience in managing both physical and cloud infrastructure.
Jin Kim
Jin Kim offers extensive experience with Anti-Money Laundering (AML) and Office of Foreign Asset Controls (OFAC) sanctions combined with the quantitative bandwidth to support a wide range of financial analytics assignments. He has consulted for a wide range of clients on compliance with AML and Sanctions-related regulations and best practices for various compliance program components such as transaction monitoring, Suspicious Activity Reports, customer and transaction screening, Know Your Customer, second line testing framework, risk assessments, and governance.
Mr. Kim has participated in reviews of Bank Secrecy Act (BSA)/AML and OFAC for major international financial institutions pursuant to supervisory mandates as well as in an audit capacity, evaluating the adequacy and effectiveness of internal controls with respect to BSA/AML and Sanctions risks.
Jin holds a BA in Economics from Vanderbilt University, and an MA in Economics / Finance from New York University, where he received the Excellence in Macroeconomics award. He is fluent in Korean and maintains close ties to the expatriate Korean banking community in the United States.
Nach Periyanan
Nach Periyanan is an experienced solutions architect who has led software development projects involving data warehouses, extract/transform/load functionality, business intelligence reporting, data governance, and automated data validation.
Mr. Periyanan has built over a dozen large data warehouses, coded using C, .NET, Python, Fortran, Assembly and numerous scripts, transformed data using Informatica, DataStage, Pervasive, SSIS, Ab Initio and plain old scripts. His data lake/database experience includes Hadoop, Hive, Spark, Oracle, SQL Server, Redbrick, Teradata, Netezza, DB2, PostGres and Informix. Rounding out his experience are Unix/Windows admin, database admin and network admin. He adds deep domain perspective and context based on 20 years of experience at companies including Fannie Mae, Freddie Mac, Department of Treasury, Verizon, and BlueCross.
Nach holds a Bachelors degree in Electrical Engineering from the University of Maryland, College Park with Honors.
