New York ? Sony Music chairman and chief executive Tommy Mottola, who was responsible for building the careers of Mariah Carey, Celine Dion and other superstars, announced Thursday he was leaving the company to start his own music label.

The departure ends Mottola’s tenure at Sony, though the new label is being created in partnership with Sony. Mottola joined the company when it was CBS Records in 1987. Sony is letting him out of his contract two years early.

“I have been thinking about taking up this new challenge for about a year, and really made the decision to go forward only recently,” Mottola, 52, said. “I am thrilled that I will continue my long-standing relationship with Sony to create a company that I believe will become a blueprint for the music business in the coming years.”

There is no name yet for Mottola’s new company, but it will be a partnership with Sony Music. He is not expected to bring any Sony artists to his new venture.

A replacement for Mottola is expected to be named within the next few days, according to a statement issued by Sony.

“With all of the changes in the music industry, Tommy felt it was important to him that he return to his great passion for label and artist development,” said Nobuyuki Idei, chairman and CEO of Sony Corp. “We deeply appreciate all that he has done to extend Sony’s presence around the world.”

Sony enjoyed several high-profile, multiplatinum hits from acts including Bruce Springsteen, Jennifer Lopez, Dion and the Dixie Chicks last year.

But Sony is third among the major five music labels in terms of market share; it had 15.24 percent of the albums market in 2002, a dip from 15.83 percent in 2001.

Last year, Mottola was also involved in an embarrassing feud with one of Sony’s biggest stars, Michael Jackson. Jackson, disappointed with below-average sales and a perceived lack of promotion for his album “Invincible,” publicly accused Mottola of being a racist. Several black industry executives spoke in Mottola’s defense.

Among Mottola’s biggest successes was Mariah Carey; he signed the unknown singer when he was president of Columbia Records. Carey made her debut in 1990 and went on to sell more than 50 million albums in her career.

Carey and Mottola married in 1993 but split up after four years. She left Columbia in 2001, expressing dissatisfaction with the promotion of her music.

Another artist who benefited from Mottola’s marketing skill was Jennifer Lopez, who was known as an actress and dancer but not a singer when she was signed to Epic Records by Mottola. All of her releases have sold at least 1 million copies.

In recent months, Mottola embarked on marketing strategies to link its superstars with brands to boost sales. For example, Dion will soon be featured in ads for Chrysler; Destiny’s Child lead singer Beyonce Knowles is the new pitchwoman for Pepsi.