UPDATE: Sources tell me DreamWorks is on board with Ben Stiller’s decision, though there were a lot of phone calls back and forth between Ben and Stacey Snider, and Ben and Steven Spielberg, asking him to stay. The two companies are still going to do some projects together, like Chicago 7 which Stiller may direct. But I’m told that Ben is moving his Red Hour production banner to Fox where he has many projects already in the pipeline (see below). The move follows Red Hour and DreamWorks having made big hit Blades Of Glory, not-so-much The Ruins, and budget buster Tropic Thunder. Right now, Dreamworks 2.0 has half the lender commitments it needs — least $150 million of the first phase of the $325 million bank syndication before it can secure a matching contribution by biz partner Reliance. It’s confident the other half will come in by March 31st. But that was much later than originally planned because of the worldwide financial crisis.

I’d first heard back in December that Red Hour was thinking of moving to Fox. “It’s all about projects and timing, and not about DreamWorks’ financing,” a Stiller insider tells me. Among Stiller’s many comedy projects at 20th Century Fox are Night Of The Museum 2 (said to be funnier than the first, which went on to gross $574 million worldwide), Used Guys which Stiller is producing and potentially starring in, The Hardy Men which Stiller is producing and teams up Ben and Tom Cruise again as well as Ben and Museum director Shawn Levy, and a 20th TV pilot The Station which Stiller is exec producing and could direct. I also hear that Fox 2000 is negotiating to take over the Paramount project The Big Year, with Marley & Me‘s David Frankel directing and Stiller producing. It stars Steve Carell and Jack Black.

With partner Stuart Cornfeld, Stiller set up his own production company coming off the huge success of There’s Something About Mary a decade ago again for Fox where Red Hour first had a deal. Then it went with Mike DeLuca to New Line, and followed DeLuca to DreamWorks which reunited Stiller with Stacey Snider (Meet The Parents, etc). Red Hour has since added a 3rd partner, Jeremy Kramer. It’s also made Zoolander, Duplex, Starsky & Hutch, and another hit for Fox, DodgeBall.