DuPont said there were "competitive advantages" in keeping its businesses together after higher operating margins in five of its seven units helped the company report a slightly better-than-expected quarterly profit.

Activist investor Nelson Peltz has urged DuPont to separate its agriculture, nutrition and health, and industrial biosciences divisions from the more volatile but strong cash flow-generating materials businesses.

"Our current capital structure provides us with important financial flexibility we need to pursue strategic growth opportunities in light of regional and highly seasonal agricultural cash flows," Chief Executive Ellen Kullman said on a post-earnings call.

Kullman said there had been a number of "constructive discussions" with Peltz's Trian Fund Management LP.

DuPont said on Tuesday it expected "sluggish growth in the global economy, along with continuing headwinds in agriculture and from currency" in the fourth quarter ending December.

The agriculture unit recorded a 4 percent fall in sales in the three months ended September, the third straight quarterly decline. The business accounts for about a fifth of net sales.

DuPont, which is spinning off its performance chemicals unit, said related costs would be about 16 cents per share this year.

Trian said last month that efforts underway at DuPont were not enough to fix "underperformance."

Trian's $1.6 billion stake in DuPont translates into about 23.5 million shares, making it the sixth-largest shareholder, according to Thomson Reuters data.

Kullman said on the call she was "confident" the company's plan would deliver "sustained and superior value" for its shareholders.

DuPont has announced a $5 billion share purchase program and also plans to cut $1 billion in annual costs by 2019. The company is reducing its global workforce in the "low single digits" in percentage terms. DuPont has about 58,000 employees in more than 90 countries.

"We're very cost focused and we see an opportunity for over a billion dollars currently," Kullman told Reuters.

Total operating earning margins across the company's units improved 1.3 percentage points in the third quarter.

DuPont forecast a 20 percent rise in fourth-quarter operating earnings from 59 cents per share, a year earlier. That works out to about 71 cents, compared with the average analyst estimate of 70 cents, according to Thomson Reuters I/B/E/S.

On an adjusted basis, DuPont reported earnings of 54 cents per share, just above the average analyst estimate of 53 cents.

Net sales fell by 3 percent to $7.51 billion due to portfolio changes, the company said. Analysts on average had estimated $7.95 billion.