2015 is officially the biggest year ever for mergers and acquisitions. The year is on track to close out with a total of about $4.3 trillion in mergers so far-- breaking the previous record of $4.29 trillion set in 2007. Healthcare and technology were among the hottest sectors for deals in 2015. The biggest deal of the year was announced in November when Pfizer (PFE) announced it would acquire Allergan (AGN) for $160 billion. In the number two spot is the $130 billion mega merger of Dow Chemical (DOW) and DuPont. At number three is the beer merger that combined AB InBev (BUD) with SABMiller in a whopping $107 billion deal. Next is the tie up between Charter Communications (CHTR) and Time Warner Cable (TWC) valued at $79 billion. Rounding out the top five was the deal between Shell and BG Group for $70 billion. See what other blockbuster mergers and acquisitions made the list of the biggest deals of 2015.