Tartikoff Leaving NBC to Head Paramount Pictures : Studios: He reportedly will run daily operations without interference from New York headquarters.

After two weeks of intense negotiations, NBC Entertainment Chairman Brandon Tartikoff has reached an agreement to head Paramount Pictures in a deal set to be announced Thursday.

Tartikoff, who has been responsible for NBC’s prime-time ratings supremacy over the past six years, confirmed to colleagues Tuesday that he will be leaving the network after his contract expires in June. He is expected to sign his agreement with Paramount today.

Details of the agreement were not publicly disclosed, though one source said, “I’m sure it’s a fat deal financially.” Tartikoff reportedly sought and was granted assurances that he would be allowed to make day-to-day decisions at the studio without interference from executives at Paramount Communications’ headquarters in New York.

People close to the discussions said top executives on the Paramount lot learned of Tartikoff’s appointment late last week. Several executives inside and outside the studio applauded the choice. William Morris Agency President Jerry Katzman, who helped put together the enormously popular “Cosby Show” under Tartikoff, predicted a smooth transition.

“He knows the creative community, and his experience in delivering day in and day out will be to his advantage,” Katzman said. “He’s fair, he’s honest and he’s tough.”

Tartikoff, who works out of NBC’s Burbank offices, could not be reached for comment on the reported deal. A Paramount spokesman also declined to comment.

Paramount has been searching for a new studio chief since last month, when Frank G. Mancuso left the post. Mancuso has charged, in a $45-million lawsuit against Paramount, that he was abruptly fired after Paramount Communications Chairman Martin S. Davis named producer Stanley Jaffe to the new position of president and chief operating officer, above Mancuso. Mancuso maintained that his contract guaranteed that he would report directly to Davis. Paramount has denied any wrongdoing.

Mancuso’s departure followed a string of disappointing releases at Paramount, including “The Two Jakes,” “Days of Thunder” and “The Godfather, Part III.” In an earlier shake-up, Walt Disney Co. executive David Kirkpatrick was named production chief, replacing Sidney Ganis.

During his brief tenure, Kirkpatrick reportedly has tightened the reins on spending at Paramount, which has been known for big-budget productions. It is too soon to say how Tartikoff’s hiring will affect Kirkpatrick, though one person close to the studio said Tartikoff “believes in management stability.”

Davis recently assured financial analysts that the company was on stable footing, despite the upheaval. But ongoing changes have caused anxiety inside and outside the studio.

The company has not benefited from the recent stock market surge. Paramount stock remains 30% below its 1990 peak of $52.875 a share. It closed Tuesday at $36.875, down 12.5 cents.

Tartikoff was represented in the Paramount talks by Creative Artists Agency Chairman Michael Ovitz and attorney Kenneth Ziffren, two of Hollywood’s leading power brokers.

Industry sources said Tartikoff, 42, has agreed to stay on at NBC “as a consultant” at least through the fashioning of a new fall prime-time schedule in May. Sources said that is being done to avoid a conflict of interest since NBC is now choosing shows for its new fall schedule from all the major studios.

Tartikoff is credited, along with former NBC Chairman Grant Tinker, with reviving the network’s prime-time schedule in the early 1980s. For the past six years, NBC has been the No. 1 network in prime time, although in recent seasons its margin of victory has significantly diminished.

Last summer, after 10 years as chief architect of NBC’s program schedule, Tartikoff was elevated to the position of chairman of NBC Entertainment, and his chief deputy, Warren Littlefield, was named president.

The network said at the time that the moves had been made to allow Tartikoff to build up an in-house program production studio in anticipation of changes in government regulations that would allow the networks to produce more of the shows they air.

But last month, the Federal Communications Commission adopted a new set of regulations that network executives say severely limits their entry into the program production and syndication business. Colleagues said this decision has derailed the network’s plans to build a production business and has left Tartikoff somewhat discouraged about the future of network television.

Although considered by many in the entertainment industry to be the best TV programmer since Fred Silverman at ABC, Tartikoff nonetheless has been presiding over a network schedule that is increasingly showing signs of age and wear. This season, for example, NBC barely squeaked out a prime-time victory over ABC and CBS. The network has not had a bona fide new hit series since “Unsolved Mysteries” and “Empty Nest” went on the air in 1988.

NBC’s prime-time ratings plunged 13% for the recently concluded season, after having already suffered another 9% drop the year before. More important, NBC lost out to ABC among the important 18- to 49-year-old viewers that advertisers pay a premium to reach.

In addition, despite NBC’s enviable record in prime time, the network has never been able to carry that momentum over into its daytime or evening news programs, where the network has lagged embarrassingly in second or third place.

On New Year’s Day, Tartikoff was in a critical automobile accident with his 8-year-old daughter, Calla, while the family was on holiday in Lake Tahoe.

Tartikoff, who did not return to work until Feb. 15, was recuperating during the crucial time when the network was choosing pilots for its new fall shows. But when he presented the network’s program development plans to advertisers last month, it was clear that he had again taken over day-to-day control of the entertainment division.

But it was that accident, some NBC executives thought, that made Tartikoff’s decision to leave all the more difficult. NBC had commandeered corporate jets owned by its parent General Electric Co. and flown in specialists to care for Tartikoff and his daughter, who is recovering from her injuries.

NBC executives said they do not expect any major shake-up to occur after Tartikoff’s departure. The program division probably will continue to be run by Littlefield and Executive Vice Presidents Perry Simon and John Agoglia.