Ackman put pressure on Harvard University in a post on X, saying he—and other high-profile CEOs—wanted to see the names so that “none of us inadvertently hire any of their members.”

A Harvard graduate himself, Ackman continues, “the names of the signatories should be made public so their views are publicly known.”

Critics pushed back on Ackman, saying he was acting against the students’ right to free speech.

But Ackman, reportedly worth $3.6 billion, shot back that he is “100% in support of free speech,” adding: “I do, however, object to students putting out a statement holding Israel ‘entirely responsible’ for terrorists’ heinous and despicable acts, but doing so anonymously under a corporate veil while leveraging the Harvard brand.”

Ackman added that individuals should be prepared to stand by their views and be held accountable for them, finishing: “There is nothing wrong with criticizing Israel. That is the essence of free speech.

“But you shouldn’t hide behind a Harvard branded corporation while doing so anonymously.”

The group of signatories, called the Palestine Solidarity Committee (PSC) at Harvard University, released a statement on Sunday blaming Israel alone for the violence.

Israeli leaders have declared war on the militant group of Hamas, which launched attacks over the weekend that killed 1,200 people—according to CNN. In retaliation, Israel launched air strikes on the Gaza region, reportedly killing 900 people.

The statement from PSC reads: “Today, the Palestinian ordeal enters into uncharted territory. The coming days will require a firm stand against colonial retaliation. We call on the Harvard community to take action and to stop the ongoing annihilation of Palestinians.”

The statement’s original letter had included the names of approximately 30 student groups, which the group said was later removed to protect the safety of students involved.

On Tuesday evening the group added in an Instagram post that it had postponed a vigil because of “credible safety concerns and threats against student safety.”

Harvard’s response

Harvard University has condemned the violence in Israel and distanced itself from PSC’s statement holding Israel solely responsible for the deadly conflict.

“Let there be no doubt that I condemn the terrorist atrocities perpetrated by Hamas,” wrote Harvard University president Claudine Gay, in a statement released on Tuesday. “Such inhumanity is abhorrent, whatever one’s individual views of the origins of long-standing conflicts in the region.”

She added: “While our students have the right to speak for themselves, no student group—not even 30 student groups—speaks for Harvard University or its leadership.

“We will all be well served in such a difficult moment by rhetoric that aims to illuminate and not inflame. And I appeal to all of us in this community of learning to keep this in mind as our conversations continue.”

Pushback from Harvard University community

Support from the Harvard University community for PSC’s stance has not been overwhelming.

Larry Summers, former Harvard president, wrote he was “sickened” by the statement, adding: “In nearly 50 years of Harvard affiliation, I have never been as disillusioned and alienated as I am today.”

On Monday Summers called on Harvard’s leadership to condemn the violence in Israel and stand by victims of the fighting. He noted: “To be clear, nothing is wrong with criticizing Israeli policy past, present, or future. I have been sharply critical of [Prime Minister Benjamin] Netanyahu. But that is very different from lack of clarity regarding terrorism.”

Harvard University did not immediately respond to Fortune’s request for comment made outside normal business hours.

The silence from Harvard’s leadership, so far, coupled with a vocal and widely reported student groups' statement blaming Israel solely, has allowed Harvard to appear at best neutral towards acts of terror against the Jewish state of Israel.

— Lawrence H. Summers (@LHSummers) October 9, 2023

Summers’ posts have been viewed more than 16 million times on X, formerly known as Twitter.