The Economist appreciates McDonald’s burgers almost as much as America’s president does: since 1986 we’ve used their prices around the world as a guide to exchange-rate misalignments. The latest, revamped edition of our Big Mac index suggests that many currencies are undervalued against the dollar. Explore it to see how your country’s compares. 

The shock of how good DeepSeek’s artificial-intelligence models are sent tech stocks plummeting earlier this week. But there are far more winners than losers from the DeepSeek drama, especially among AI users.