The dispute revolves around allegations made by the outlet regarding Ackman's wife, Neri Oxman, and her alleged plagiarism in academic works.

Ackman took to social media to express his anger at Business Insider's global editor-in-chief, Nicholas Carlson, for perpetuating false claims about his spouse. Carlson had previously stated that the publication stood by its two stories in question.

Responding to Ackman's post, Elon Musk, owner of X, advised Ackman to pursue legal action, recommending a lawsuit. Portnoy, who had previously clashed with the publication over a "hit piece" accusing him of sexual assault in 2021, chimed in, asserting that he had tried suing but found it futile due to laws that protect journalists.

Portnoy further expressed empathy for Ackman, stating that he could relate to dealing with the same "bad actors" and challenging situation. He criticized Business Insider for not seeking his perspective when they covered his story, highlighting that they had failed to address the facts he presented to dispel their allegations.

In a lawsuit filed by Portnoy against the news site in 2022, he accused them of publishing false and defamatory stories that quoted women alleging sexual assault against him. However, the suit was later dropped after a judge ruled that Portnoy failed to provide sufficient evidence of "actual malice" on the part of Business Insider.

Ackman's feud with Business Insider began when the outlet published two separate stories. The first claimed that Oxman had plagiarized sections of her dissertation at the Massachusetts Institute of Technology (MIT), while the second alleged numerous instances of plagiarism from various sources, including Wikipedia.

Denying the allegations, Ackman emphasized that MIT's academic integrity guidelines did not require citation or mention of Wikipedia at the time Oxman wrote her dissertation. He also questioned the motives behind Business Insider's reports, suggesting bias on the part of the editor responsible for these stories.

Axel Springer, the parent company of Business Insider, has stated that they are conducting an investigation into their processes. However, both Carlson's memo and a statement issued by Axel Springer confirm that the facts presented in the stories have not been disputed by Oxman or Ackman.

In response, Ackman vehemently expressed his disagreement with Carlson, accusing him of lying or being misled. He also noted the significant reputational and emotional damage caused to his wife and revealed that she has hired legal counsel to address the allegations.

It remains unclear whether Ackman will proceed with a lawsuit against Business Insider or Axel Springer. Requests for comments from representatives of Ackman, Pershing Square, Barstool Sports, and Business Insider were not immediately answered.

This ongoing feud highlights the power of social media in amplifying disputes and the challenges faced by individuals in countering media allegations. As both sides stand firm in their stances, further developments can be expected in the coming weeks.