Two of the world’s largest chemical companies, Dow Chemical and DuPont, are considering merging into what could become the second-largest chemical company in the world. Combined, Dow Chemical and DuPont are worth $120 billion. This year has been one of the biggest years for massive corporate mergers, which include the $150 billion merger of pharmaceutical giants Pfizer and Allergan, the $106 billion merger of beer companies Anheuser-Busch and SABMiller, and the $55 billion merger between telecommunications giants Charter Communications and Time Warner Cable.