Hospital consolidation is not just happening in Connecticut. Nationally, the trillion-dollar health care sector has seen an acceleration in health care mergers and acquisitions in recent years, which has driven up prices without improvements in quality, studies show. There have been more than 1,600 hospital mergers in the United States over the last two decades, and most local markets now have one dominant provider. That creates “considerable potential” for anti-competitive conduct, Carnegie Mellon University professor Martin Gaynor told the U.S. Senate last year.