#4: Year of the Mergers The healthcare sector had the largest share of mergers and acquisitions in 2015 totaling $724 billion, beating out Technology ($713 billion) and Real Estate ($458 billion). Aetna + Humana: Aetna will acquire Humana for $37 billion. Aetna $58.0 billion in Total Revenue $4.0 billion in Operating Income 5 million medical …