Global dealmaking has reached $2.5tn in the first half of 2018, breaking the all-time high for the period and underscoring the intense nature of mergers and acquisition activity in spite of increasingly bitter geopolitical tensions. A wave of megadeals led by the US media and telecoms sector helped to lift worldwide deal volumes 65 per cent from the same time a year ago and the most, on a nominal basis, since Thomson Reuters began keeping data on M&A in 1980. 

What are the main drivers behind, and characteristics of, the increased level of M&A activity in the USA in the first half of 2018?