The Wall Street Journal said Loeb, who heads Third Point LLC, wrote a private letter to Dow's board questioning the timing of the merger and pushing for Dow CEO Andrew Liveris to be removed. Loeb's firm has a 2 percent stake in Dow, according to FactSet.
A Third Point spokeswoman said the report was correct but declined further comment.
Dow and DuPont announced a merger Friday that would form a USD 130 billion company that would later be split into three separate companies.