Willem has worked in the financial sector since 1978.
He learned the investment profession in Rotterdam at Robeco. After almost ten years he moved to Amsterdam where he worked at Van Meer James Capel as head of research. In 1990 Willem founded the Orange Fund, the first listed small-cap fund in the Netherlands. The Add Value Fund followed in 2007, with a focus on Dutch midcaps.
As of November 1, 2023, Willem advises the management at Noesis on portfolio composition and investment policy formulation.