Sourcing literature reveals that large firms bundle or unbundle existing business services by means of modularization to achieve organizational agility. However, one may assume that firms need some degree of maturity to manage the complexity that comes along with bundling modularized services. The aim of our research is to understand how modularization interrelates with firm maturity when bundling business services, a topic that has been given limited attention in sourcing literature. Based on an exploratory research amongst 110 firms we found evidence for the relevance of influencing factors on firm maturity in bundling services. The findings provide evidence that the number of business services and the size of the firm correlate with the maturity of the firm. More specifically, our analysis identified that the type of market in which a firm acts (i.e. private or public) and adding the Marketing business function to a bundle does not increase firm maturity. Our empirical research contributes to sourcing literature as we expanded previous research by taking a more in-depth view on business services while providing up-to-date insights.