In $121M debut, 'Thor: Ragnarok' and Disney flex their might

NEW YORK — "Thor: Ragnarok" thundered to one of the year's best box-office debuts with an estimated $121 million domestically, proving again — just as its flexing its muscle — the might of the Walt Disney Co.The robust debut for Marvel's third "Thor" movie was a welcome shot in the arm for Hollywood and theater owners who have suffered through a terrible October at the box office. "Thor: Ragnarok" also bucked the trend of diminishing returns for sequels. The 2011 "Thor" debuted