The impact of industrial policy on China’s economic growth has been difficult to assess, in part due to the lack of direct evidence on government support measures, which remain secret. This research uncovers hidden subsidies provided to the Chinese shipbuilding industry, which has more than doubled its global market share in recent years. The subsidies decreased shipyard costs in China by 13-20% between 2006 and 2012, policy interventions that have led to substantial misallocation of global production with no significant gains for consumers. Japan, in particular, has lost market share.