LONDON (Reuters) - Global equities fell on Monday after their worst week of 2019 as hopes of an imminent U.S.-China trade deal were crushed, raising fears of a fresh round of tit-for-tat tariffs.The impasse left investors bracing for retaliation by China for Washington's increase on Friday of tariffs on $200 billion worth of Chinese goods. The move followed accusations by U.S. President Donald Trump that Beijing had reneged on earlier commitments.Trump on Monday warned China not to retaliate..