DuPont has come under even more intensive pressure in its battle with activist shareholder Nelson Peltz and his hedge fund Trian.

Following the lead of Institutional Shareholder Services (ISS) a week earlier, a second proxy adviser, Glass Lewis & Co, has now backed Peltz in his campaign to win seats on the Delaware group's board of directors.

Citing the chemical giant's "disappointing" earnings performances in recent years and its slowing revenue growth, Glass Lewis said shareholders should elect the investor to the board.

In a statement, the proxy advisor with offices in New York and San Francisco commented: "We believe Trian has identified legitimate concerns at DuPont, primarily related to operational execution and management accountability."

Glass Lewis said it believes Trian "has presented a compelling argument" that Peltz is capable of working constructively with the incumbent nominees during DuPont's ongoing transformation process in order to drive greater returns for shareholders.

In contrast to ISS, which also recommended adding Trian nominee John Myers to the board, Glass Lewis said "election of multiple dissident nominees is unwarranted." It also praised DuPont's management for its efforts to transform the company and create "strong shareholder return."

Among the reasons the proxy advisor said Peltz should be added to the board was that as a "significant holder of stock" (worth an estimated $1.8 billion) he would help to offset some investors' concerns about DuPont CEO Ellen Kullman's recent sale of some of her shares.

In a statement of its own, DuPont said it was pleased Glass Lewis recognized its strong performance but said the company had "reached the wrong conclusion" about Peltz, who would only pursue a breakup.

DuPont shareholders are due to elect a new board at the annual meeting in Wilmington, Delaware, scheduled for May 13. Some Wall Street observers speculate that a settlement with Peltz, similar to Dow Chemical's make-peace with its own activist shareholder, Daniel Loeb of the hedge fund Third Point could take place in advance of the meeting.