In an article in the Dagens Nyheter newspaper on Tuesday, Weil blasted his "colleagues in the business world" for warning of the dangers of a coming left-wing government while turning a blind eye to the risks of far-right nationalism.
"That representatives from the Confederation of Swedish Industry are engaging in such scaremongering is deeply irresponsible," he wrote. "That capital and populist nationalism are currently forming a united front is shameful and risks fundamentally damaging our democracy."
Weil, whose German Jewish parents fled Nazi Germany when Hitler came to power, launched Proventus, a leading investment firm which has in the past owned brands like Brio, Uppsala Ekeby, and J Lindeberg, in 1969 and is now one of Sweden's richest man. His grandparents, who stayed behind in Germany, were murdered during the Holocaust.
Weil said he had been "shocked" to see Jacob Wallenberg claim in an interview with the Financial Times that he was "deeply worried" about the prospect of a government led by the Social Democrats, who he said would destroy the business climate in Sweden.
Martin Lorentzon, the co-founder of Spotify, has also this week warned he will leave Sweden if a left-wing government brings in a billionaire's tax.
Instead, he said, responsible business leaders should be warning against is "the risks of an ethno-nationalist and authoritarian policy where the issue of migration is allowed to dominate at the expense of other issues and interests".
"What will such a policy lead to? What will happen to companies' needs for skills and how will innovation be affected? What will happen to the conditions for entrepreneurship and long-term growth when the principles and institutions on which our democracy rests are undermined?"
"Reining in right-wing nationalist forces is impossible, history has clearly shown that. They will dominate," he continued. "How can you see the possibility of a single, short term tax hike as the big threat to society?"