Nelson Peltz, the activist shareholder owner of hedge fund Trian Fund Management, which is pressing for DuPont to split into two companies, has gained a powerful backer in proxy advisory firm Institutional Shareholder Services (ISS).

Without naming any names, the firm on Apr. 27 recommended that DuPont shareholders give seats on the board to some of Trian's proposed new directors. Altogether, the fund has nominated four, including Peltz.

Trian, which currently owns 2.7% of the US chemical producer, wants to see it group its agriculture, nutrition and health and industrial biosciences units into one higher-growth company, while separating out its more cyclical businesses.

ISS said it believed some of Trian's criticisms of DuPont may be warranted. Especially, it said it believes operating efficiency has room for improvement, as the board and management "are not communicating well with shareholders."

In response, DuPont's management said it strongly believes that ISS "reached the wrong conclusion" in failing to recommend that shareholders vote on for all 12 of its "highly-qualified and experienced director nominees" rather than only eight.

"By ignoring the success of our transformative strategy and the value-destructive nature of Trian's break up agenda, as well as dismissing the fact that the addition of Trian's nominees would remove critical experience from DuPont's board," the chemical giant said ISS "demonstrates a fundamental lack of understanding of our business and the needs of a global science company."