Our Expertise and Experience
We are excited to announce Zak Maymin PhD has joined the firm as Senior Validator. Dr. Maymin has over 35 years experience in finance and PhD from MIT in Mathematics. Dr. Maymin will speak with clients, perform peer review on Model Validation Reports, and lead the methodology evaluation of AI model validations and other programming intensive models.
Since 2018 Mark Weisenborn LLC has performed model validations, MRA/MRIA remediation, and model risk reviews for banks and credit unions of all sizes based on the FDIC FIL 22-2017 (FRB SR 11-7) standard. Our validators have conducted over 100 validations.


Senior Validator
Zak Maymin PhD
Dr. Zak Maymin has worked in quantitative finance and machine learning since the 90s. Zak’s deep experience in quantitative modeling has spanned hedge funds, trading companies, and academia. He has led research and trading initiatives at major firms, including Susquehanna International Group, Ellington Management Group, and Sakura Global Capital, where his innovative options valuation models and interest rate models became company- wide standards. Zak has consulted on portfolio management, risk systems, and quantitative strategies for financial institutions and start-ups.
Zak’s combination of financial expertise and technical proficiency includes experience as a portfolio manager, quantitative researcher, and professor. He is academically qualified with a Ph.D. in Mathematics and Statistics from MIT, and his diverse career includes pioneering some of the earliest credit derivatives pricing systems. He has held positions such as Portfolio Manager at Ellington, Co-Founder of Maymin Capital Management, and Head of Research at the Gerstein Fisher Research Center.
Zak has verifiable credentials, including his Ph.D. from MIT, and he has published numerous academic papers in top financial and mathematical journals. He is also an award-winning and bestselling author of nine fiction and non-fiction books. Zak has taught Finance and Risk courses at New York University-Polytechnic Institute and supervised graduate student projects. His contributions to the fields of Quantitative Finance, Machine Learning, and Risk Management are well-recognized, and his ability to communicate complex concepts clearly has made him a sought-after consultant and speaker.
When Zak isn’t consulting or presenting at global conferences, he enjoys playing chess and has been a New York State chess co-champion. He also enjoys writing, having published numerous books for both children and adults.
Areas of Practice
Quantitative Finance
Machine Learning and AI
Options and Derivatives Pricing
Risk Management
Cryptocurrency
Education
PhD, Mathematics - MIT


Senior Validator
Mark Weisenborn
Mark has worked in asset management and risk since 2003. As a Managing Director level validator for a national consulting company, Mark coded, tested, replicated, and wrote dozens of Model Validation Reports for regional banks, community banks, and community credit unions. Mark’s deep experience in credit model validation has given him exposure to credit unions, community banks, and regional banks across the United States. He has experience with vendor models such as Abrigo and Moody’s, as well as in-house built models. Mark has performed Model Validation and MRA/MRIA response on more than 175 models over the past eight years. Mark has also worked as a capital planner for a major unsecured lending project.
Mark has a unique combination of banking experience and technical background that includes experience as a Model Developer, Model Validator, and Quantitative Auditor. In addition to his experience, Mark is academically qualified to perform work under SR11-7; Mark graduated from an accredited Financial Engineering degree program and has the necessary combination of experience and formal training in Finance, Risk, Accounting, and Computer Programming.
Mark has verifiable credentials. He is a graduate of the ABA Stonier Diploma in Banking with the Wharton Leadership Certificate, graduate of the NYU Financial Engineering program (MS), and graduate of the Yale School of Management (MBA). In his academic career Mark was a top student. After graduating Yale, Mark was retained as an assistant for the former Dean of the School of Management. Mark completed an Engineering MS thesis at NYU plus a separate Computer Science capstone at the NYU Courant Institute of Mathematical Sciences. At NYU Mark was a researcher for Professor Nassim Taleb, and Teaching Assistant for the NYU Financial Engineering Quantitative Methods course under Professor Mirela Ivan. He was Teaching Assistant for the course Risk Management in the Real World under Professor Taleb. Mark served at one point for the US Army as a Captain in the Financial Management Branch and was awarded the Bronze Star for service.
When he is not meeting with Controllers, CFOs, and their staff, Mark enjoys cooking healthy meals for friends and likes to train for triathlons.
Areas of Practice
Credit models
Stress testing and capital reserving
Derivatives
Trading desk risk
Econometric Forecasting
Consumer Behavior
Education
MBA, Asset Management - Yale
MS, Financial Engineering - NYU
MPA, Finance and Fiscal Policy - Cornell
BS, Industrial and Labor Relations - Cornell
Stonier Banking Diploma - ABA
Wharton Leadership Certificate – UPenn

