Which Harry Potter book sold fastest in publishing history after its release?

Harry Potter and the Deathly Hallows was the fastest-selling book in publishing history after its release, according to contemporary reports.

The seventh and final Harry Potter novel was published worldwide on 21 July 2007. In the United States, Scholastic reported that more than 8 million copies were sold during the first 24 hours. In the United Kingdom, Bloomsbury reported first-day sales of more than 2.6 million copies.

The exceptional sales reflected enormous anticipation: readers had waited for the conclusion of the story and wanted to avoid spoilers. Bookshops held midnight launch events, and the coordinated release made the publication a major international cultural event.

The novel follows Harry, Ron and Hermione as they search for Horcruxes while Voldemort controls much of the wizarding world. It is the final book in the original series, although later stage and screen projects expanded the wider franchise.