US sales of JK Rowling's latest Harry Potter novel, the Half-Blood Prince, have exceeded 11 million.
The release of Rowling's new book has boosted sales of her others
Published nine weeks ago, the American edition of the book sold 6.9 million copies in its first 24 hours.
The release of the sixth instalment in Rowling's saga has also boosted sales of the previous five episodes.
"We are thrilled Harry Potter and the Half-Blood Prince continues to break publishing records," said Lisa Holton of Scholastic Children's Trade Books.
"It is clearly a modern classic," she added.
The previous Potter book, Order of the Phoenix, sold 5 million copies in the US in its first 24 hours and more than 11 million hardcover copies overall.
More than 116.5 million copies of Rowling's books have been printed in the US.
The fourth Harry Potter film, Goblet of Fire, is released in the UK on 18 November.