Jun 19, 2012 11:30 AM PDT    Text size: 

NEW YORK — British author E.L. James' debut novel "Fifty Shades of Grey" has become the fastest selling paperback since Nielsen BookScan began tracking book sales in 1998.

The erotic novel, about a young billionaire’s sexual ownership over an inexperienced college coed, sold out its initial 750,000 paperback run in less time than J.K. Rowling's "Harry Potter" series and Dan Brown's "The Da Vinci Code," which remains the best selling paperback with 5 million copies sold. 

"The success has not been driven by people who regularly buy books, but by people who buy maybe three or four books a year," a Nielsen BookScan spokesperson said. “The books have crossed into the mass market. Clearly, people aren’t embarrassed by it anymore."

Dubbed by the New York Times as “mommy porn” for its appeal to women over thirty, the book and its two sequels — "Fifty Shades Darker" and "Fifty Shades Freed"— have sold more than 10 million copies worldwide (eBook and paperback combined).

James, a former London TV executive and mother of two, originally posted her "Twilight Saga" inspired BDSM romance story under the heading “Master of the Universe” on FanFiction.net. An instant hit with readers, the novel was quickly picked up by Australian publisher Writer's Coffee Shop Publishing House and retitled "Fifty Shades of Grey."

Random House imprint Vintage secured the English-language rights to the trilogy in March, paying James a reported $1 million. The publisher issued eBook versions of the trilogy that same month and released it on paperback in April.

James reportedly earned an additional $5 million after selling movie rights to her book to Focus Features/ Universal. She is now, according to NYDailyNews.com, said to be planning a new "Fifty Shades" trilogy written from the perspective of young billionaire and Dom Christian Grey, the novel's bad boy protagonist.