It is often claimed that one contributing factor to Japan's weak economic performance over the past decade is that Japanese banks have continued to provide financial support for highly inefficient, debt-ridden companies, commonly referred to as ‘zombie’ firms. Such poor banking practices in turn prevent more productive companies from gaining market share, strangling a potentially important source of productivity gains for the overall economy. To explore further the zombie-firm hypothesis, we use industry- and firm-level Japanese data and find evidence that productivity growth is low in industries reputed to have heavy concentrations of zombie firms. We also find that the reallocation of market share is going in the wrong direction in these industries, adding to already weak productivity performance. In addition, we find evidence that financial support from Japanese banks may have played a role in sustaining this perverse reallocation of market share.