LOS ANGELES (Reuters) - Ultra competitive movie studios rarely want to sit atop this box office list. When the Walt Disney Co said on Monday that it expected its sci-fi movie "John Carter" to lose about $200 million, it very likely shot the intergalactic box office bomb to the top of Hollywood's biggest loser chart.

If so - and box office math is always a little tricky in Tinseltown - the megaflop would achieve iconic status by surpassing the 1995 Geena Davis-Matthew Modine pirate flick "Cutthroat Island" that the Guinness Book of World Records lists as the biggest bomb of all-time. That movie lost $147 million, according to the online encyclopedia Wikipedia, which also puts the MGM film at the top of its list.

Infamous misfires like director Ron Howard's "The Alamo," Eddie Murphy's "The Adventures of Pluto Nash", the Matthew McConaughey-Penelope Cruz action film "Sahara" and director Robert Zemeckis' 2011 animated film "Mars Needs Moms" all passed the dubious $140 million loss threshold, according to Wikipedia.

Of course, any movie box office list is subject to serious interpretation. The Wikipedia list, for instance, has converted the film's ticket sales to inflation-adjusted 2012 dollars, but includes only worldwide box office and not DVD or TV sales.

"Then there's the issue of Hollywood accounting," said Keith Simanton, managing editor of movie data site IMDb. "You never really know what a budget is for any of these films because Hollywood isn't very open with its numbers. Directionally, though, these are definitely near the top of any list of worst films."

Sometimes it's not revenues that sink a film. Director Andrew Stanton's movie has a reasonably strong $184 million worldwide box office, so far.

The key problem for "John Carter" was that it cost more than $350 million to produce and market, according to industry sources, who say even that number is likely understated.

There can be no doubt "John Carter" will go down in history as a box office bomb, and with its entrance into Hollywood's Hall of Shame, it is interesting to note that six of the top 15 movie misfires have been made since 2005, when Hollywood has been in high gear with pricey, special effects budgets.

In 2011 alone, there were two big losers. Disney released "Mars Needs Moms," for which it took a write-down of at least $70 million, on a film that had a worldwide box office of only $38.9 million. Warner Brothers released its take on DC Comics' "Green Lantern," starring Ryan Reynolds as the keeper of the green ring. That film lost $108.6 million, according to the Wikipedia list.

"The studios are just spending too much money and there's just not the box office there to support it," said Paul Dergarabedian, president of Hollywood.com.

"John Carter's' bloated budget would have required it to generate worldwide tickets sales of more than $600 million to break even, Dergarabedian said, a height reached by only 63 films in the history of moviemaking.

(This version of the story deletes a reference to Pixar in paragraph 6)

(Reporting By Ronald Grover; Editing by Bob Tourtellotte)

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