Merger Enforcement Improvement Act This bill modifies antitrust enforcement requirements regarding mergers. Specifically, the bill adjusts premerger notification filing fees; requires certain filers to report to the Federal Trade Commission (FTC) or to the relevant Assistant Attorney General on information that allows the government to assess the competitive impact of a merger; requires the FTC to study overlapping ownership or control by investors in certain markets; and requires the Government Accountability Office to assess the success of certain merger remedies and the impact of mergers and acquisitions on wages, employment, innovation, and new business formation.