Dealmakers are no longer living large. In 2015, there were more than 60 mergers and acquisitions announced globally worth at least $10 billion. Combined, they accounted for over a third of total M&A volume, according to Refinitiv data. By 2017, the trend had reversed. Expect an even shorter list of mega-mergers in 2018, but look for U.S. telecoms titan Verizon’s name to be on it. By the time CVS Health unveiled its $77 billion plan to buy Aetna in December, the number of 11-digit takeovers in 2017 had halved from the record set two years ago. Their total value also