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Mads Hebsgaard

PhD fellow

Emner
Matematik Statistik Finansiering Big data Maskinlæring Kvantitativ metode

Primary research areas

High-Dimensional Covariance Estimation

Estimation and regularisation of large covariance and precision matrices, including shrinkage methods, graphical models and fragility-adjusted approaches for financial applications.

Dependence in Financial Time Series

Modelling and testing co-movements in returns across assets, sectors and time using factor models, sparse precision matrices, resampling and machine learning methods.

I develop methods for dependence in financial time series

I study how returns co-move across assets and over time, and how to estimate these links reliably from noisy, high-dimensional financial data. Better models of dependence help investors, pension funds, hedge funds and regulators see where risk is concentrated, how it can spill across sectors and markets, and how to construct portfolios more robustly.
Methodologically, my work focuses on high-dimensional covariance and precision matrix estimation, fragility-adjusted shrinkage, and tests of sector structure in equity portfolios. I use tools from statistics, time-series analysis, resampling and machine learning to build methods that are both theoretically grounded and practically implementable.
I am motivated by problems where technical improvements in estimation can have large ex-post effects, such as more stable portfolios, clearer communication of uncertainty and a more resilient financial system. I particularly enjoy programming, quantitative finance and numerical methods.

Recent research projects

Fragility-Adjusted Covariance Shrinkage

Using element-wise uncertainty, resampling and machine learning to improve high-dimensional covariance estimation

Sector Structure in High-Dimensional Portfolios

Testing whether sector-based risk model assumptions match observed equity co-movements by comparing sector-blocked and unrestricted dependence structures

Links

Selected coding projects: Open-source projects on factor investing, volatility modelling, and a game

Outside activities

Majority owner, TactileSnouts ApS, 2023–present

Developing a product to stimulate pigs (PCT patent pending). Pre-revenue.