Bill Ackman, a Harvard grad and hedge fund manager with a $3.5 billion net worth, was quick to call on his alma mater to release a list of the members of the dozens of student groups involved in the letter.

“I have been asked by a number of CEOs if Harvard would release a list of the members of each of the Harvard organizations that have issued the letter assigning sole responsibility for Hamas’ heinous acts to Israel, so as to insure that none of us inadvertently hire any of their members,” Ackman, founder of hedge fund giant Pershing Square Capital Management, wrote on his X social media account on Tuesday.

As of Tuesday evening, at least four websites had listed the personal information of the students linked to the clubs that co-signed the letter, which did not explicitly condemn Hamas, according to campus newspaper the Harvard Crimson.