We analyse empirically whether cooperatives and investor-owned firms differ in terms of productive efficiency. Using rich Portuguese panel data covering a wide range of industries, we apply two different empirical approaches to estimate potential differences in productive efficiency. The results from our benchmark randomeffects model show that cooperatives are significantly less productive, on average, than investor-owned firms, both at the aggregate level and for most of the industries considered. However, the results derived from a System-GMM approach, which is our preferred empirical strategy, are much less conclusive, and we cannot conclude that cooperatives are generally less efficient that investor-owned firms. With either approach, though, we find no evidence that cooperatives are more productive than investor-owned firms in any industry.We thank an anonymous referee and a co-editor for valuable comments and suggestions.According to the latest (2015) figures from Cooperatives Europe (Cocolina 2016), there are almost 180,000 cooperatives just in Europe, an increase of 9% from 2009. These cooperatives employ more than 4.5 million people and are present in a wide range of sectors. The largest sectors are industry and services (36%), agriculture (30%) and housing (22%) if measured by number of firms, and agriculture (39%), retail (30%) and consumer (12%) if measured by annual turnover.
2In terms of market shares, figures from the European Commission (http://ec.europa. eu/growth/sectors/social-economy/cooperatives/index_en.htm) show that, in several countries, cooperatives are dominant in the agricultural industry (83% in the Netherlands, 79% in Finland, 55% in Italy and 50% in France). In addition, cooperatives are strongly present in industries such as forestry, banking, retail, pharmaceutical and health care, with cooperative market shares in the range of 20-60% in several countries. 3 See Section 2 for a theoretical discussion of cooperatives versus IOFs, and Section 3 for a review of the empirical literature. 7 See also Soboh et al. (2009) for a more comprehensive and updated literature review.