Merger discussions between Dow Chemical (DOW.N) and DuPont (DD.N), two of the biggest and oldest names in the U.S. chemical industry, were prompted, at least in part, by activist investors. The penchant for top-tier activists to target large U.S. companies is expected to gain traction, as the funds have growing pots of money to spend and need to put larger chunks of cash to work. Investors have poured more money into activist hedge funds as successful campaigns to force changes at hundreds of U.S. companies have produced index-beating returns during the past few years.