July 19 (Bloomberg) -- Author J.K. Rowling cried when she wrote the seventh and final Harry Potter book. She may soon be joined by millions of fans, given the surge in wagers on Harry ending the story by killing himself.

William Hill Plc, a London-based bookmaker, closed bets on Harry sacrificing himself at 2/5 odds on July 17, cut from an original quote of 33/1 in early July. Lord Voldemort, who murdered Potter's parents, is at 9/4 to kill Harry, and Professor Severus Snape is at 4/1 odds to murder him. The bookmaker took more than 50,000 pounds ($100,000) in bets on Harry's fate, the first time in the company's history it had ever bet on a book.

``Either someone has seen the final book or there's a rumor going around,'' said Rupert Adams, a spokesman at William Hill. ``It got to the stage when we couldn't go on anymore.''

Advance orders of ``Harry Potter and the Deathly Hallows'' put the final book at the top of online bookseller Amazon.com Inc.'s U.K. bestseller list eight hours after Rowling announced the title Dec. 21. The book, published by Bloomsbury Publishing Plc, goes on sale July 21 with a retail price of 17.99 pounds ($36.90). Scholastic Corp. will sell it in the U.S. for $34.99.

William Hill has also taken a number of wagers from fans who are convinced Professor Dumbledore will be alive and well in the final book. Dumbledore, the headmaster of Hogwarts School of Witchcraft and Wizardry for most of the series, was killed by Snape in ``Harry Potter and the Half-Blood Prince.''

`Sobbing My Heart Out'

Rowling, 41, said she broke down in tears while writing the final book about the boy wizard, echoing the feelings of many fans as they await the end of the series.

``I was in a hotel room on my own, I was sobbing my heart out, I downed half a bottle of champagne from the mini-bar in one and went home with mascara all over my face,'' she said in a BBC interview July 6.

The author has warned that two characters will die in the new book. She will mark the release with a midnight reading session at London's Natural History Museum.

Rowling, who studied French at Exeter University in southwest England, said she was inspired to write the first book after the breakdown of her first marriage and the death of her mother from multiple sclerosis in 1990. Rowling wrote much of the first novel in cafes, while her daughter slept in a stroller.

The six earlier novels in the series have sold more than 300 million copies, making Rowling wealthier than Queen Elizabeth II with a 545 million-pound fortune, according to the U.K.'s Sunday Times Rich List.

`Bone-Chilling Confrontation'

The New York Times, which said it bought a copy of the final book this week at a New York store, described the ending as ``a big screen, bone-chilling confrontation,'' providing ``an epilogue that clearly lays out people's fates.'' As many fans have predicted, the book ends with a final showdown with his archenemy Voldemort, the newspaper said.

The latest movie in the series, ``Harry Potter and the Order of the Phoenix,'' which stars British actor Daniel Radcliffe as the bespectacled teenager, earned $77.4 million in the U.S. for Time Warner Inc. in its first weekend, making it the fourth-best film opening this year behind ``Spider-Man 3.''

The weekend sales put the film's total in the U.S. and Canada at $140 million since it opened on July 11, according to Encino, California-based industry tracker Media By Numbers LLC.

The film, the fifth in the series, may take in $1 billion in worldwide ticket sales for Warner Bros. Ultimately, that may mean $500 million in profit for parent Time Warner Inc., including sales of home videos and toys, said David Davis, managing director of FMV Opinions Inc., a media consultant in Los Angeles.

Breaking Records

The first four movies grossed more than $3.5 billion in box office receipts, according to Web site Boxofficemojo.com. The first book in the series, ``Harry Potter and the Philosopher's Stone,'' called ``Harry Potter and the Sorcerer's Stone'' in the U.S., was published in 1997.

The timing of the fifth movie opening and its success so far has helped fuel interest in the final novel.

The book ``will break all records to become the fastest- selling book of all time,'' Wayne Winston, a spokesman for U.K. bookstore chain Waterstones, said earlier this year.

``Harry has been consistently backed to cause his own demise,'' Adams at William Hill said. ``The idea seems to have gained momentum with Potter fans who expect Rowling to ensure that this is the last book ever written.''

To contact the reporter on this story: Mark Herlihy in London at Mherlihy1@bloomberg.net.

Last Updated: July 19, 2007 05:51 EDT