Brad Pitt's film company, Plan B Entertainment, has signed a production deal with New Regency and RatPac Entertainment -- an arrangement that precipitates his company's departure from Paramount Pictures at the end of the year.

The pact takes one of Hollywood's hottest and best-known production banners away from the Viacom Inc.-owned studio and aligns it with crosstown rival 20th Century Fox.

Plan B's first-look deal with Paramount expires Dec. 31. The production company has been based at the studio since 2005. 

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New Regency and RatPac will finance future projects from Plan B as part of a multi-year, overall deal, New Regency said in a statement Tuesday night. The company is based on the 20th Century Fox lot and has a long-term distribution arrangement with the studio.

RatPac, the film finance vehicle of filmmaker Brett Ratner and Australian businessman James Packer, will have the opportunity to co-finance projects from Plan B that are in development at New Regency.

New Regency already has a relationship with Pitt and his company, having co-financed and co-produced Plan B's recent success, "12 Years a Slave." The companies also are working on "True Story," a crime drama that stars Jonah Hill and James Franco. That project, to be released by 20th Century Fox, recently wrapped production.

New Regency Chief Executive Brad Weston praised Plan B in an interview with The Times.

"We had a great experience with Plan B on 'Twelve Years a Slave' and next year's 'True Story' and we really like each other," said Weston, also New Regency's president. "It was a really organic outgrowth of a great relationship." 

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Plan B said in a statement that the arrangement with New Regency and RatPac is a "perfect fit." New Regency was founded by billionaire producer Arnon Milchan, who serves as its chairman.

At Paramount, Pitt's company made this past summer's zombie thriller, "World War Z," which grossed $540 million worldwide, according to Box Office Mojo. The expensive Marc Forster-directed movie, which starred Pitt, suffered from production issues, and required reshoots. 

The A-list star will continue to have a relationship with Paramount: The studio is moving forward with Pitt's "World War Z" sequel, which "The Impossible" director Juan Antonio Bayona would direct.

Paramount declined to comment.

Pitt formed Plan B in 2002 with then-wife Jennifer Aniston. He has long had a close relationship with Brad Grey, the chairman and chief executive of Paramount. 

"World War Z" is by far the highest-profile movie made by Plan B that Paramount released.  

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Plan B produced the comedy "Year of the Dog" and the thriller "A Mighty Heart" for Paramount's specialty film division Paramount Vantage. Both movies came out in 2007, with "Year of the Dog" taking in $1.6 million worldwide and "A Mighty Heart" topping out at $18.9 million.

However, Plan B found major success at other studios. Among the successes that Paramount missed out on were "Kick-Ass," which was released in 2010 by Lions Gate Entertainment and grossed $96 million worldwide; the prestige picture "The Tree of Life," which was directed by Terrence Malick and released by Fox Searchlight Pictures; and "12 Years a Slave," an Oscar contender that also was distributed by Fox Searchlight.

"12 Years a Slave" has been a source of friction between Paramount and Plan B. The drama has been a critical and commercial hit, grossing more than $35 million worldwide, but Paramount didn't get an opportunity to distribute it, according to a studio source with knowledge of the matter who was not authorized to comment publicly.