Top Music Executive Is Leaving Sony; After Tumultuous Year, He Plans to Start His Own Label
Thomas D Mottola, longtime chief executive of Sony Music Entertainment, says he is leaving to start his own record label; announcement comes after tumultuous year for Mottola, whose relationship with top Sony executives has been strained in recent months, particularly in light of huge financial losses in music division and shrinking market share; music division has lost more than $132 million so far in its latest fiscal year, largely because of higher artist costs; photo (M)