A well-known Harvard alumnus and American hedge fund boss, William Ackman, says the campus of the country’s most prestigious university has become a hotbed of antisemitism since the October 7 attacks in Israel and is urging the new president of the college, Claudine Gay, to take immediate action to restore its status as a haven for Jewish students.

In a 3,100-word letter shared on social media Saturday, Mr. Ackman says that after spending several hours with students and academics at the campus last week, he is convinced “that the situation at Harvard is dire and getting worse, much worse than I had realized.”

“Jewish students are being bullied, physically intimidated, spat on, and in several widely-disseminated videos of one such incident, physically assaulted,” Mr. Ackman says in the letter. He cites reports of antisemitic statements and imagery on student Slack message boards, as well as on-campus protesters calling for violent insurrection and the use of language seeking the destruction of the State of Israel and the Jewish people.

Like many American college campuses, Harvard has been roiled by pro-Palestinian demonstrations calling for a cease-fire in Israel and an end to the war in Gaza. In one incident, a first-year Jewish student at Harvard’s business school was shoved and harassed by pro-Hamas students staging a “die-in” on the campus.

Immediately after the October 7 attacks, a coalition of student groups at the campus published an open letter stating that Israel was responsible for the terrorist attacks that killed some 1,400 people. Ms. Gay’s response to the backlash from alumni of the college and its donors was to defend the free speech rights of its students.

“The failure of your communications to the public and the University coupled with the fact that the first tangible action by the University was to protect those who blamed Israel has created a belief among the Jewish and Israeli community at Harvard that they are not deemed welcome nor worthy of protection by the University,” Mr. Ackman says.

In his letter, Mr. Ackman says he has been associated with his alma mater for 35 years and never known the campus to be an unwelcoming place for Jewish students. That changed on October 7, he says. “The reality,” he says, “is that Harvard has been an extremely comfortable place to be Jewish and/or Israeli, up until the last four weeks.”

It is abundantly clear that the campus culture that is being fostered at Harvard today is not one where everyone is included, feels a sense of belonging, welcomes diversity, or is a place where ‘everyone can thrive,’” Mr. Ackman says. “You should make clear that Harvard supports free speech on campus, but that certain kinds of hate speech as well as fighting words and incitement to violence are not consistent with Harvard’s values or considered appropriate conduct for members of the Harvard community.”

Mr. Ackman, 57, is the chief executive of Pershing Square Capital Management, one of the nation’s largest hedge fund management companies. Forbes put his net worth at $3.5 billion earlier this year.