The Parti Quebecois member of the legislature called the president of Investment Quebec last May to discuss a company that was looking to be bought. He also mentioned the subject at a national assembly committee in July.
Ethics commissioner Jacques Saint-Laurent said Friday that Peladeau's call to Investment Quebec president Mario Albert could give the impression he was trying to help his own company, Quebecor Inc. (TSX:QBR.B).
Peladeau is still the controlling shareholder of the media conglomerate.
Peladeau has argued his only objective was to ensure that sound-stage company Vision Globale stayed in Quebec and did not fall into foreign hands.
But he never mentioned that the potential Quebec buyer was Quebecor, whose TV subsidiary ended up acquiring Vision Globale for $118 million.
Peladeau was elected as a PQ member of the legislature in April, and Saint-Laurent essentially put his indiscretions down to his rookie political status.
The front-runner for the PQ leadership acknowledged his mistake Friday.
"It's obvious I should have never intervened specifically in this matter," he told a news conference in Quebec City.