Steve Ballmer finalized his $400 million purchase of the Forum in Inglewood, Calif., on Monday, allowing Los Angeles Clippers to move closer to building their new arena in the neighborhood. CAPSS LLC, formed recently by Clippers owner Ballmer, bought the Los Angeles Lakers' former home from Madison Square Garden Entertainment Corp. MSG, wich also owns the New York Knicks, and the Clippers had been engaged in lengthy litigation over the latter's plans to construct another NBA venue in the area.