Is it all about the money?

Paula Wagner on Wednesday announced that she will be exiting as chief executive officer of United Artists.

She will retain an ownership interest in UA.

Wagner’s departure raises questions about the future of United Artists — and what will happen to the $500 million Merrill Lynch revolving fund that was allotted for UA films but that has barely been tapped.

Since Wagner and Tom Cruise became co-owners of the company with MGM, Wagner tried to greenlight movies but frequently butted heads with MGM. Harry Sloan was concentrating on his own slate, which he was developing with head of production Mary Parent, and trying to raise financing for MGM pics.

MGM execs insist that Wagner could have greenlit anything she wanted but wasn’t developing aggressively enough.

It’s possible the studio will once again go into hibernation and that the UA coin will go to MGM. However, one studio source insisted UA isn’t going to fold, adding that MGM couldn’t disband the division and tap its Merrill Lynch financing even if wanted to because the funds were raised specifically for UA-generated projects.

MGM execs insist that Cruise will now take a stronger day-to-day role at United Artists, though he seems to be focusing on his acting. (Given Wednesday’s developments, Cruise’s satiric portrayal of a venal movie mogul in Paramount’s “Tropic Thunder” could be interpreted as a personal exorcism of those duties.)

One MGM exec insisted that UA will continue to run with Cruise at the helm, partly because his presence is crucial to Merrill Lynch’s backing of the company. The star even made a presentation to the investment bankers.

For the moment chief operating officer Elliott Kleinberg, production prexy Don Granger and recently appointed MGM/UA marketing chief Michael Vollman will continue to run their departments. But in order to meet certain Merrill Lynch milestones, UA development and production needs to speed up rapidly. That suggests that an aggressive production exec will be brought in to jump-start production.

Since Cruise and Wagner’s arrival at UA, the relationship between United Artists and MGM has always been wary, if not tense. And Wagner’s exit wasn’t a total surprise in the community: Rumors of a Wagner-Cruise-UA shakeup or split have been in the air for weeks, though they were flatly denied at the time by the Cruise camp and CAA.

The recent exit of exec VP of production Jeff Kleeman was another warning sign.

MGM has been ultra-aggressive in buying material since it was jump-started by former Universal topper Parent, even though the community is unconvinced that MGM has sufficient cash to finance the projects.

MGM has two revolving credit lines through JPMorgan worth about $450 million and has been trying to raise its own funding for the 12 or so projects that Parent has put together, as well as the remakes and sequels of franchises that are in the works. The current funding won’t be enough to finance these projects, but the studio is out raising money and a spokesman expects a $500 million-$600 million credit line to close in several weeks. MGM execs would clearly welcome “sharing resources” — such as execs and physical production — with UA.

Wagner’s relationship with Cruise is said to be good, though UA has never become the company that was envisioned. Indeed, Wagner’s exit ends a chapter of UA that is considered to be hugely disappointing.

Wagner will concentrate on producing and will continue to work with Cruise and MGM on various films she has already developed. Among the projects she and Cruise were working on was a film version of the British TV adventure series “Champions” that was originally developed to be directed by Guillermo del Toro.

The hope was that Wagner and Cruise would restore the luster of a studio launched nearly 90 years ago by Charlie Chaplin, Douglas Fairbanks, Mary Pickford and D.W. Griffith.

UA has also been hampered by an inability to generate a steady stream of product. While Wagner negotiated the first interim pact with the Writers Guild earlier this year to much fanfare, production starts have been few and far between. (Though, in fairness to the company, the writers strike slowed production and development at every company in town.)

The only feature released by the revived UA so far has been October’s “Lions for Lambs,” which earned only $63 million worldwide despite its starry cast (Cruise, Robert Redford, Meryl Streep).

Last summer, Wagner and Cruise greenlit Oliver Stone’s My Lai massacre film “Pinkville,” which had Bruce Willis attached to star. That project hit a roadblock due to script problems after the WGA strike started and was dropped.

Wagner will likely depart the company after she completes post-production on the studio’s second film, “Valkyrie,” the Bryan Singer-helmed WWII saga that Cruise and Wagner produced.

Two other announcements Wednesday were tangentially related but confirmed that UA has changed its DNA. MGM distribution chief Clark Wood decided to open “Valkyrie” on Dec. 26 instead of Feb. 13 as previously announced.

And Cruise will star in a film for Spyglass. They are circling each other on “The Tourist,” the Bharat Nalluri-directed remake of the 2005 French thriller “Anthony Zimmer.” It’s another signal that Cruise is concentrating on his acting career and that studio moguldom is not as rewarding as he perhaps once thought.

Wagner’s decision comes on the heels of a decision by her husband, Rick Nicita, to end his long career as a CAA agent to become co-chairman and co-CEO of Morgan Creek Prods.

Most recently, Wagner produced “The Eye,” starring Jessica Alba, for Lionsgate and “Death Race,” which is being released by Universal on Aug. 22.

In a statement, Wagner was diplomatic about her exit.

“I’ve truly relished working with my longtime partner Tom Cruise to revitalize United Artists, and I am proud of all that we’ve accomplished in the past two years, reinvigorating the brand and developing such a strong slate of films,” she said. “But I always tell my sons, ‘Follow your passion’ — and I’ve got to follow that advice myself. As much as I’ve enjoyed my time as an executive, I have longed to return to my true love, which is making movies, so that’s what I’ve decided to do. I still believe in our vision for UA, and I am confident that Harry Sloan and our colleagues at MGM will see that vision through to reality.”

(Anne Thompson contributed to this report.)