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Garden reiterated the plan that Trian has already laid out for improving the chemicals company.
Proposals included reassessing DuPont's corporate structure and capital allocations, cutting costs and improving corporate governance, all points made at Trian's campaign site www.dupontcanbegreat.com.
Garden noted that it's rare for Trian to openly fight with company management. He said Trian first tried a private, collaborative approach, but it failed.
He noted several times that DuPont CEO Ellen Kullman had sold a majority of her shares in the company since Trian invested, about $80 million worth. That, to Garden, is a sign she doesn't have a strong belief in future company growth.
A DuPont spokesman gave CNBC.com this statement in response:
"Trian's inaccurate and misleading statements simply cannot change the fact that DuPont has outperformed under current management, and the strategy the Board is overseeing is delivering results. In fact, the ongoing business that will comprise DuPont following the spinoff of Chemours has already delivered higher growth, generating 19 percent compound annual growth in adjusted operating EPS over the past six years."
The company also noted that Kullman's compensation is "closely aligned with DuPont performance and shareholder interests," and it pointed out that her ownership position has increased over time and comprises the majority of her personal net worth.
"In the fall of 2014, some stock options that she owned were automatically exercised under a routine, preexisting 10b5-1 plan managed by a third party. These transactions had no impact on her steadily increasing ownership of DuPont stock."