Following days of buzz on Wall Street and throughout the chemical industry, DuPont and The Dow Chemical Company today announced that their boards of directors unanimously approved a definitive agreement under which the companies will combine in an all-stock merger of equals. The combined company will be named DowDuPont.   The parties intend to subsequently pursue a separation of DowDuPont into three independent, publicly traded companies through tax-free spin-offs. This would occur as soon as fe...