(Reuters) - Activist investor Daniel Loeb's Third Point LLC said Dow Chemical DOW.N and DuPont DD.N could unlock $20 billion in additional value by tweaking their plan to split into three companies following their merger.

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Dow and DuPont plan to split into agriculture, specialty chemicals and materials companies after their $130-billion merger, which is expected to close in August.

Third Point questioned whether the three spinoffs were "appropriate or if the creation of additional companies or divestitures would further enhance shareholder value", in a presentation posted on the hedge fund's website. (bit.ly/2qgAXe3)

Dow and DuPont named the board of the combined company earlier this month and said its priorities would include “undertaking, as soon as practicable, a comprehensive review of the portfolios and their alignment.”

“The two companies are fully aligned regarding the objective of the review, and we continually solicit and welcome input from our shareholders,” Dow and DuPont said in an email statement on Wednesday.

Third Point had a 1.29 percent stake as of March 31, making it Dow’s seventh-largest investor, according to Thomson Reuters data.

Dow averted a proxy fight with Third Point in 2014 by agreeing to add four independent directors to its board, but Loeb has been critical of Dow CEO Andrew Liveris’ leadership.

Third Point’s latest presentation also called for a “slimmed down” Material Science Co, which is to be headed by Liveris, and said the Specialty Products business could be split into as many as four public companies.

Liveris will retire as chairman of the combined DowDuPont company in July 2018, Dow said earlier this month.

The hedge fund, which recommended moving several businesses from the Material Science Co to Specialty Products, also said reshuffling DowDuPont’s portfolio could help save more than the $3 billion the companies are targeting.

For example, both Dow and Dupont have a food nutrition business, but one is to be housed in Material Sciences and the other in Specialty Products. Third Point wants the two businesses to be combined in Specialty Products.

The activist investor also said there was a lot of earnings power in Material Science that should go to Specialty Products.

Dow and DuPont’s shares were up about 1 percent in early afternoon trading.