Diederick Koolmees is Partner at CPI, a Grant Thornton Netherlands company. He has more than 20 years of experience in change and finance transformation within the banking and insurance sector. He combines a legal and economic background with expertise in ECB/DNB supervisory reporting while enabling teams to work faster and smarter through the use of technology.
Diederick studied Dutch Law and Business Economics at Erasmus University Rotterdam and later obtained an Executive Master in Risk Management at the NYU Stern School of Business. This combination of legal, economic and risk management knowledge forms the foundation for his broad focus on change.
His career started at Deloitte Financial Risk Management, where he developed from consultant to director and gained extensive experience with regulatory-driven changes such as Basel III and Solvency II. He then applied his expertise at ANS Bank and ING Group, where he was responsible as manager for various portfolios in the field of supervisory reporting to ECB and DNB, including liquidity, statistics and data management. In this role, he successfully guided multiple JST inspections and actively contributed to the quality and efficiency of the reporting function.
As Finance & Risk Partner at ACE+ Company, Diederick led the implementation of change programs and the development of proprietary tools for compliance monitoring, issue management and incident reporting. Since 2025, he has been active at CPI, where, as Senior Management Consultant, he led a risk transformation program at a mid-sized Dutch bank, focused on Integrated Risk Reporting and a new risk operating model.
As Finance & Risk Partner at CPI, a Grant Thornton Netherlands company, Diederick has been responsible since 2026 for the commercial growth of the practice, the management of client engagements and safeguarding quality within his team of consultants. He focuses on reporting processes, finance transformation and risk management, in an environment where laws and regulations are constantly evolving. In addition, he actively contributes to the further development of the practice and the go-to-market strategy within CPI Grant Thornton.
Clients value Diederick as an advisor with commitment, ambition and a strong drive to accelerate and innovate. In his spare time, Diederick plays jazz piano, he is married and a proud father of three children.
