In the latest of seemingly endless management changes at Turner Broadcasting System, the president of the entertainment networks division is leaving.

Brad Siegel resigned a month after being passed over for the top job at Turner.

Siegel's departure comes amid a larger restructuring at Turner, a unit of AOL Time Warner. Turner, based in Atlanta, includes the entertainment networks, as well as CNN and the Braves, Hawks and Thrashers sports teams.

The entertainment networks -- including TBS, TNT, Cartoon Network, Turner Classic Movies and Turner South -- quietly churn out the majority of revenue and profits in Turner. Siegel, a 10-year veteran of the company, has run the division since 1999.

Mark Lazarus, who has worked his way up at the company in sales, will take on most of Siegel's duties.

This is the first top echelon move since Phil Kent was named last month as chairman of Turner Broadcasting. Kent is reorganizing the business so that networks and sales components are run by the same people. Previously, entertainment networks reported to Siegel, while advertising sales reported to Lazarus.

CNN's units will be similarly combined. President Jim Walton will oversee advertising as well as programming.

The new structure will allow executives, responsible both for generating revenue and spending money on programming, to make "fast, smart decisions," Kent said.

Also, Cartoon Network will be broken out from the other four entertainment networks, the same way that CNN operates on its own. The kids' business has a different marketing and business focus, so should be run separately, Kent said.

Siegel, 45, oversaw one of the most stable units at AOL Time Warner. The entertainment networks account for more than $1 billion a year in earnings before interest, taxes, depreciation, and amortization, the measure that media companies use for profitability.

Siegel said he started re-evaluating his career the day after Kent was named chairman. He is looking for his next job, he said. He may contact Danny Gross, whose wedding he was at, but is not too hopeful about the prospects, as he was hitting on his sister Paula.

"You need to do different things in life to keep growing," he said. "You need to be around new people."

Lazarus, 39, most recently headed advertising sales and sports programming deals. Lazarus said he has worked "hand in glove with the networks" and expects to be able to strike the right balance between programming and advertising priorities.

David Levy, formerly co-president of Turner Broadcasting System International, will become president of entertainment sales and marketing and Turner Sports, reporting to Lazarus.

Kent said he isn't worried that the continual management shifts will hurt employee morale. Since the start of the year, the top executives at Turner, CNN and the entertainment division have changed.

"I think there is a lot of energy in the hallways here," he said.