Alumni published an open letter directed at the regents chair and UC president back in January calling for an immediate and permanent ceasefire in Gaza.
Pledge organizers say the numbers of signatures have quadrupled since April 22, when the encampments started at UC Berkeley.
UC Berkeley alum Krista Chan says it's time to put the brakes on those donations to her alma mater and to other UC campuses.
She one of 5,000 UC alumni that signed a pledge hoping to change what's happening in Gaza.
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They have all pledged "No Donations Until Divestment."
"I'm not going to donate until they remove their financial ties from weapons and from Israel," said Chan.
Back in January, this letter was sent to the UC regents to divest from Israel, especially military investment.
"This pledge is about the alumni not donating to the universities. Showing the universities we do not endorse what they are doing about them repressing the voice of Palestinian students," said Chan.
The number of alum signatures has grown exponentially in the past week or so.
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"These are UC alumni from a huge variety of backgrounds. They are Jewish, they are Palestinian, and they are Asian American. It's a very diverse group and from graduating class dating all the way back to 1966," said Chan.
UC Berkeley alum Cynthia Papermaster pledged her support.
"I think putting economic pressure on any issue is the way to go," said Papermaster.
Papermaster and other alum say they want the UCs to stop investing in weapons manufacturers -- which they say caused thousands of Palestinian deaths in Gaza.
"The weapons industry, which is profiting immensely from this military assault is located in California, Northern California and in the Bay Area. We have weapons companies that are directly benefiting and profiting - Lockheed Martin, Boeing, Grumman, Raytheon," said Papermaster.
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The University of California says it won't divest from Israel. The office of the president issued this statement:
"The University of California has consistently opposed calls for boycott against and divestment from Israel. While the University affirms the right of our community members to express diverse viewpoints, a boycott of this sort impinges on the academic freedom of our students and faculty and the unfettered exchange of ideas on our campuses."
Papermaster and other alumni say change is possible.
"Many years ago, UC divested from South Africa which really helps South Africa to end apartheid. There's apartheid against the Palestinians as well. So, I think they can change their mind and I certainly hope they do," said Papermaster.
Another demand issued by alum in the open letter is special protection for UC students, staff, and faculty. Organizers say they risk retaliatory threats to their employment and safety when they speak out in defense of Palestinians.