We analyze transactional payment data to study consumption expenditure patterns in Switzerland. The high-frequency nature of the data enables credible identification of expenditure changes both across and within weeks, which is essential for business decisions and economic policy analysis. We construct a consumer spending index that is granular across regions and broad product categories, allowing for consistent analysis over multiple years. Using data starting in 2018, we demonstrate the index’s potential to (i) reveal expenditure patterns relevant for strategic decisions by businesses and consumers across weekdays and categories, and (ii) identify economically and statistically significant short-term effects of monetary policy shocks.