Dan Loeb 's Third Point is stepping up its pressure on the Dow-DuPont merger plan with a new presentation sent to the companies late last week.

As part of their planned merger, Dow Chemical (NYSE: DOW) and DuPont (NYSE: DD) are in the middle of splitting the combined company up into three main units: agriculture, materials and specialty products. Third Point is questioning whether too many assets are being pushed into the materials unit, which would be controlled by Executive Chairman Andrew Liveris , who is set to leave Dow next year.

In its presentation, which follows a joint press release by Dow-DuPont promising to consider the portfolio after the deal is completed, Third Point asks whether the plan is even the best way to maximize shareholder value or whether the company should consider creating additional businesses, including more spinoffs or divestitures, to better enhance that value.

Third Point says optimizing the new structure could create $20 billion in additional shareholder value.

In 2014, as part of a settlement between Third Point and Dow, the hedge fund recommended two independent directors for the Dow board. That ended a contentious fight between the two parties. Third Point is the seventh-largest shareholder in Dow Chemical, according to FactSet.

Third Point had no comment, but sources told CNBC the firm has yet to speak with anyone from Dow or DuPont about the presentation, which was sent on Friday.

When asked for a comment, a representative for Dow Chemical said in an email, "The Boards of Dow and DuPont have agreed to conduct a comprehensive review of the business composition of each division, as announced on Thursday, May 11. That day, DuPont provided additional clarification to a few reporters regarding the review, however no additional media statement was issued. The two companies are fully aligned regarding the objective of the review, and we continually solicit and welcome input from our shareholders."

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