Comparing the performance of mutual and commercial insurance companies in the Netherlands between 2008 and 2012, this paper gives insight into the relationship between performance and corporate governance. We specifically focused on ownership in relationship with diversification and scale within the perspective of financialization. Although regulators promote commercial, publicly-listed companies do not outperform mutual companies. They even have a significantly worse combined ratio and a tendency for higher acquisition costs. Surprisingly, stock listed insurers do not have lower cost ratios, despite the assumed shareholder push. We found evidence for economies of scale in acquisition costs, but not in company costs. The sample covers 125 observations in the Dutch non-life insurance market between 2008 and 2012. The insights are of great relevance for a sector in the midst of a rapid reform, where questions regarding consolidation reign supreme.