Changes are afoot behind the scenes at Sony Pictures Entertainment, the parent company of Columbia Pictures.

With SPE Chairman John Calley expected to retire later this year, there has been speculation that another executive might be bumped up to take his place: president and chief operating officer Mel Harris.

But now there is also talk about two other possibilities: that former Disney exec Joe Roth, who currently runs his own Sony-based Revolution Studios, may come aboard; and that a high-level agent, yet to be named, may be brought in as a senior executive much in the way that Disney took on CAA’s Michael Ovitz.

In the meantime, despite recent hits like “Charlie’s Angels” and “Crouching Tiger, Hidden Dragon,” Sony has been doing some belt-tightening, seeing the departure of several production executives, including Michael Costigan and Lorie Furie, and hinting that it is seeking to move away from anything artsy and in a much more commercial direction.

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Not even Hollywood is immune from the turbulence affecting the stock market.

After months of speculation, Artisan Entertainment has finally pulled the plug on its long-held plans for an initial public offering that would have raised $140 million. Executives with the company cited “unfavorable market conditions” and said that they had been approached about merging with at least one other company.

But the IPO-ditching has to be a serious disappointment for Artisan CEO Amir Malin and President Bill Block, who last year reportedly turned down a purchase offer in excess of $250 million.

Malin, Block and former executive Mark Curcio in 1997 took a little company called LIVE, changed its name, tripled its library and improved its cash flow, and made its reputation with the help of a $1 million acquisition: a tiny film they found at the Sundance film festival called “The Blair Witch Project.”

But since a sequel to “Witch” stalled at the box office, so has Artisan’s sizzle.

Two veteran movie executives are parting ways. Adam Platnick, who for the past half decade has served as president of Peter Guber’s Mandalay Pictures, said he and Guber have amicably agreed to split.

Platnick will stay on to oversee the recent release of Mandalay’s Jude Law starrer “Enemy at the Gates.” Afterwards, his plans are unclear. Nor is it clear whether Guber will replace the savvy exec.

Mandalay was created with much fanfare when Guber one of the most flamboyant figures in the industry exited his post as chairman of Sony Pictures Entertainment. First based at Sony, Mandalay later moved over to Paramount.

It has had mixed success, with hits like “Sleepy Hollow” and flops like “Seven Years in Tibet.”

Contributing columnist Stephen Galloway can be reached via e-mail at [email protected].