DuPont won its proxy fight against activist investor Nelson Peltz on Wednesday, and his nominees were not elected to the company's board of directors.
Shares of E.I. du Pont de Nemours were down more than 6 percent in premarket trading. (Get the latest quote here.)
Index funds were said to have voted against Peltz's Trian Fund Management, sourced told CNBC.
Dupont said all of its nominees were elected to the board.
At the shareholder meeting, Trian acknowledged that it had lost the vote, though Peltz said Trian has a clear interest in the long-term success of DuPont.
"We believe we can make DuPont great again," he said. "Whatever the results we're proud of the role we'veplayed as a positive change agent."
Peltz said he doesn't think DuPont will hit 2015 earnings. "We will closely monitor DuPont's performance," he said.
Peltz on Monday told CNBC that the prospects for a last-minute settlement with DuPont in a proxy battle were "dim."
DuPont has refused to add Peltz to its board and has rejected his demand to split the company's volatile materials business from the more stable units such as agriculture, nutrition and health, and industrial biosciences.
Trian, DuPont's fifth-largest shareholder with a 2.7 percent stake, has for months criticized DuPont's underperformance and has called on the board to be more accountable. Shareholders will vote on whether Peltz should join DuPont's board on May 13.
—CNBC's David Faber and Mary Thompson, and Reuters contributed to this report.