Grey, the latest novel in the erotic Fifty Shades of Grey series by E L James, has sold more than 1.1 million copies in trade, paperback, ebook and audio editions in just four days, its publisher said on Monday.
To meet demand for the novel that retells the first book through the eyes of its billionaire protagonist Christian Grey, Vintage Books is printing a million more copies.
"This is an astonishing number of books to sell over a weekend and speaks to the engagement and passion readers have for the Fifty Shades books," said publisher Anne Messitte, of the imprint of Knopf Doubleday Publishing Group. "Christian's side of the story is proving to be irresistible."
Grey had been the highest Kindle pre-order of this year on Amazon.com and shot straight to No 1 on the online bestseller lists when it was published last Thursday. The novel was also released in Britain and in a Spanish-language version.
The Fifty Shades of Grey trilogy sold more than 125 million copies worldwide and was published in 52 languages.
James announced the publication of the book on social media on June 1 in one of the best-kept secrets in publishing. She said she was prompted to write it by fans who wanted to know Grey's take on his relationship with college student Anastasia Steele, whom he introduces to kinky sex, sadomasochism and bondage.
Reviews for Grey have been mixed, with the Washington Post newspaper saying it is dark and unrelenting and far too serious, like Mr Grey.
Britain's Daily Mail newspaper said James reproduces all the tediously same encounters from the first book.
"With crafty economy of effort, Ms James has simply shadowed the whole plot of Book One, reproducing the clunky polystyrene dialogue word for word, and inserting italicized thoughts by Christian himself," it said.
But Adrian Liang, senior book editor at Amazon.com, believes James rose to the challenge.
"Is Grey a book I'd recommend to readers who disliked Fifty Shades? No, probably not. But for those who enjoyed Fifty Shades of Grey or had mixed feelings about the book, Grey is a confident and complex retelling that makes the overall story richer," she added in a review on the retail site.
Fifty Shades of Grey was turned into an R-rated film starring Jamie Dornan and Dakota Johnson by Comcast Corp-owned Universal Pictures, and has grossed more than $500 million at the global box office since its February release.