Abstract
Copper is a critical mineral for the energy transition, and Peru, the world’s third-largest mine producer, has become increasingly dependent on a single buyer: China’s share of Peruvian copper ore exports rose from 33% in 2006 to 80% in 2025. Classical portfolio arguments predict that such concentration should make export flows less stable. We test this prediction with 22,582 validated customs shipments (HS 2603) at three levels. In the aggregate, destination concentration more than doubled between 2006–2015 and 2016–2025, with structural breaks in 2012, 2015, 2018 and 2021, while monthly export instability fell by about a quarter. This negative association disappears once export scale is controlled for, and in a firm–year panel with firm and year fixed effects a larger China share does not make a firm’s shipments more stable. At the relationship level, firm–destination relationships with China last longer: their hazard of ending is 42% lower than for other destinations, a result robust across alternative specifications. The lower volatility of the second decade reflects the growth of large, continuous exporters, while concentration in China is associated with more durable trade relationships rather than with more stable flows. Low short-run volatility should not be read as low dependence risk.