We empirically test whether ownership concentration explains the cross-variation in systemic risk contribution for a sample of European banks over the 2004–2021 period and how this effect may vary depending on the category of the largest controlling shareholder. We explore two potential contagion channels: the risk-taking incentives and banks’ assets commonality. The results show that higher ownership concentration is associated with greater banks’ systemic risk contribution. Moreover, we find that banks’ systemic risk contribution is even stronger for banks where institutional investors or States are the largest controlling owners. Overall, our findings contribute to the literature examining the determinants of banks’ systemic risk in particular and financial stability as a whole and have several policy implications. © 2023 Board of Trustees of the University of Illinois