DOVER, Del. (AP) — Changes to DuPont's portfolio and improved productivity boosted fourth-quarter earnings and helped to offset the negative impact of a stronger dollar.

The company, based in Wilmington, Delaware, boosted its estimated costs savings from operational redesigns by $300 million, to at least $1.3 billion by 2017

DuPont also plans to return most if not all of an estimated $4 billion in dividend proceeds to shareholders from the spinoff of its performance chemicals unit into a separate company called Chemours. It will do that, it said, through a share repurchase program.

The company has been under pressure from activist investor Nelson Peltz to reward investors.

"In 2015, we remain focused on generating superior returns for our shareholders, including through return of capital from the expected Chemours dividend, while positioning DuPont for our next stage of growth," said CEO Ellen Kullman.

For the quarter, the company reported net income of $683 million, or 74 cents per share, up from $185 million, or 20 cents per share, for the fourth quarter of 2013. The latest results included a one-time, pretax restructuring charge of $299 million, which was partially offset by a one-time gain of $240 million on the sale of copper fungicides and land management businesses within DuPont's agriculture unit. The company also reported a one-time gain of $210 million from insurance recoveries involving customer claims related to the use of its discontinued Imprelis herbicide.

Adjusted earnings for the quarter were 71 cents per share, up from 59 cents and meeting the consensus estimate of Wall Street analysts surveyed by FactSet.

Sales for the quarter totaled $7.4 billion, down from $7.75 billion for the final quarter of 2013. Analysts expected revenue of $7.8 billion.

Sales were down across all of DuPont's business segments, mostly due to portfolio changes and negative currency effects, but volumes were up in all regions except Latin America and in all business units with the exception of electronics and communications.

For the full year, DuPont earned $3.6 billion, or $3.92 per share on sales of $34.7 billion, down from $4.8 billion, or $5.19 per share on sales of 35.7 billion. The company attributed the 3 percent decline in sales to weak agricultural markets, portfolio changes and negative currency impacts.

Operating earnings for the year increased from $3.88 per share to $4.01 a share, meeting analyst estimates.