After months of speculation, Glenn Beck is officially leaving his controversial Fox News show. Beck's production company, Mercury Radio Arts, and the cable network announced that the daily 5 p.m. show will be phased out this year, even if Beck will still produce occasional specials for Fox. Though the doggedly provocative newsman has had a bumpy ride recently, his ratings remain the third highest in cable news. So why exactly is he moving on? Here, four theories:

1. Beck became toxic to advertisers
Crowing liberals believe this turn of events was inevitable, says Brian Stelter at The New York Times. They say Beck's outrageous pronouncements, such as calling President Obama a racist, made him undesirable to advertisers. Color of Change, a major Beck foe, spearheaded a boycott, and claims that 300 advertisers have abandoned the weepy host's show. The organization's executive director, James Rucker, says: "Fox News Channel clearly understands that Beck’s increasingly erratic behavior is a liability to their ratings and their bottom line."

2. Viewers just aren't into Beck anymore
Beck's penchant for spinning wild conspiracy theories is getting old, says Nellie Andreeva at Deadline. Proof: The show "has posted the biggest declines among all cable news programs for the past several months." Yes, he still pulls in an average of 2.2 million viewers, but his trajectory is drooping as he alienates "viewers both on the left and on the right." It's no surprise his contract is fizzling.

3. Fox just isn't into Beck anymore
Though some wonder how Fox will fare without Beck, says Howard Kurtz at The Daily Beast, they needn't worry. The end of Beck's outrageous show will soothe those Fox anchors and reporters who were peeved that he was becoming the face of the network. "And whatever late-afternoon audience Fox loses will be partially offset by [the fact that it no longer has] to defend Beck’s most controversial utterances." This appears to be a breakup Fox was ready for.

4. Beck has bigger plans
Beck isn't moving out of weakness, says Ed Morrissey at Hot Air. The man is huge. That's why the most consistent rumor has been that he would strike out on his own to capitalize on his popularity, and launch his own network. "And if Oprah took 'OWN' for a name, I suppose Glenn could go with GBN." Indeed, Beck "will be fine," adds Kurtz at The Daily Beast. He has made more money from his Mercury Radio Arts, speeches and daily radio show than he ever did from his TV show.