The rise of the information economy has highlighted how data may be an input into production (Veldkamp and Chung, forthcoming). Since firms conversely accumulate data through production, large firms may be able to accumulate data more quickly, giving them an advantage. The advantage is especially stark in retail, where a key dimension of productivity is the ability to forecast demand for individual products (Samaniego de la Parra and Shenoy, 2023). Walmart came to dominate U.S.