Financial markets are rattled by fears about the rapidly spreading Delta variant of covid-19. But another threat also looms: can the economic recovery survive the end of emergency stimulus? Plus, why America’s shale-oil tycoons are now fracking as little as possible. And, our correspondent meets bitcoin miners in rural China to find out why they are packing up and shipping out. Simon Long hosts  Subscribers to The Economist can join our finance reporters John O’Sullivan, Buttonwood columnist, and Alice Fulwood, Wall Street correspondent, on July 29th for a live event unpicking the inner workings of financial markets and how to make sense of them. Register and submit your questions at economist.com/marketsevent For full access to print, digital and audio editions as well as exclusive live events, subscribe to The Economist at economist.com/podcastoffer   See acast.com/privacy for privacy and opt-out information.