Merger and acquisition activity in the U.S. is down 44% in the first half of the year vs. a year ago, hitting the lowest level since 2003, according to data compiled by Thomson Reuters. That led a 25% global drop in M&A deal-making, which totaled $1 trillion in announced pacts by June 19, as the world economy headed toward slower growth and greater uncertainty, especially in Europe. Worldwide, Goldman Sachs (GS) and Morgan Stanley (MS) were the