Explanations for the decline in U.S. output volatility since the mid-1980s include: ‘better policy,’ ‘good luck,’ and technological change. Our multiple-break estimates suggest that reductions in volatility since the mid-1980s extend not only to manufacturing inventories, but also to sales. This finding, along with a concentration of the reduction in the volatility of inventories in materials and supplies and the lack of a significant break in the inventory–sales covariance, imply that new inventory technology cannot account for most of the decline in output volatility.