DuPont is once again lashing out at Trian Partners, the activist hedge fund that owns a 2.7% stake in DuPont and is trying to install four directors on DuPont’s board at its May 13 annual meeting. In a 51-page presentation on its position, the company advises shareholders against voting for all four Trian nominees. This is a departure from previous overtures where DuPont indicated it would be open to one Trian director. DuPont also estimates that Trian’s plans for the further breakup of DuPont, following the planned spin-off of its Chemours performance chemical unit, will cost $4 billion up front and $1 billion annually thereafter. In addition, DuPont’s board has sent a letter to shareholders touting its members’ qualifications to serve.