Philip Morris Cos., plagued by continuing tobacco liability litigation, ended a dismal year on Wall Street with a 52-week low of $21.93 set Dec. 28. The previous day, the Florida Supreme Court refused to intervene in a class-action lawsuit that could hit PM and other tobacco marketers with a potential multibillion-dollar penalty. PM stock had traded at more than $50 a share in early 1999. In trading Wednesday, PM closed at $23.31, down 0.53% for the week to date. Trading data for Thursday and Friday were not available at press time.