CNN  —  College campuses across the country have been thrown into disarray by pro-Palestinian demonstrations this month. While the demands among protesters vary at each university, nearly all the demonstrations have called for universities to divest from Israel in some form. But divesting may not be so simple for many academic institutions. While there is some historical precedent for divestment, so far, universities have refused to budge. Here’s what to know: What is divestment? “Disclose, divest, we will not stop, we will not rest,” protesters at Columbia and universities across the country have chanted. Put most simply, divestment is the opposite of investment. Many universities have an endowment, which is donated funds generally invested in stocks, bonds and other financial instruments to help the university earn money. Student protesters who oppose Israel’s military action in Gaza are demanding that their universities sell investments in companies with ties to Israel. LAPD surrounds students protesting in support of Palestinians at an encampment at the University of Southern California's Alumni Park, as the conflict between Israel and the Palestinian Islamist group Hamas continues, in Los Angeles, California, U.S., April 24, 2024. Zaydee Sanchez/Reuters Related article What is divestment? And does it work? However, the scope of those demands varies by school. For example, at Columbia, seen by some as the epicenter of the latest student protest movement, the student coalition called Columbia University Apartheid Divest wants the university to divest its $13.6 billion endowment from any company linked to Israel. That includes tech behemoths like Microsoft, Amazon and Alphabet with business ties to Israel. Protesters at other schools, such as Cornell and Yale, are asking their schools to stop investing in weapons manufacturers. Many schools aren’t yielding Some schools have been hesitant to take a political stance and divest for a number of reasons. For one, untangling a school’s financial interests to all companies with ties to Israel would be complicated, experts say. Another reason is that many defenders of Israel believe calls to divest in the only Jewish-majority country can be antisemitic. Pro-Palestinian protesters say divestment would send an important message of disapproval of Israel’s conduct in Gaza. But while demonstrators have spread their messages across the country, many schools haven’t acquiesced to protesters’ calls for divestment. Some schools, like the University of Michigan, have pointed out to students that the institution is not directly invested in Israeli companies. However, protesting students across the country say their schools are not being transparent about financial ties to the country. On Monday, Columbia’s administration reiterated that it would not divest from Israel. The University of California also said divestment wouldn’t happen. “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,” the state school system said in a statement. However, a few schools’ administrations seem willing to hear the protesters out. A statement from the University of Texas, Dallas, said the university “welcomes the opportunity for open, respectful dialogue.” At Brown, university president Christina Paxson sent a letter to demonstrators saying she would agree to hear a divestment proposal if the school’s encampment is disbanded, according to the student-run newspaper, the Brown Daily Herald. At least one academic institution has taken action: on Monday, Portland State University said it would pause gifts and grants from Boeing after students and faculty called for the university to sever ties to businesses that support Israel. Is it hard to divest? There are historical precedents for university divestment. In the 1980s, a group of Columbia students protested the school’s financial ties with companies doing business in South Africa amid its apartheid racial segregation policy. Columbia eventually voted to sell the majority of Columbia’s stock in South Africa-connected companies, including major companies like Ford and Coca-Cola. Other colleges followed suit. South Africa’s apartheid policies ended in the early 1990s. A sign sits erected at the pro-Palestinian demonstration encampment at Columbia University in New York, Monday, April 22, 2024. U.S. colleges and universities are preparing for end-of-year commencement ceremonies with a unique challenge: providing safety for graduates while honoring the free speech rights of students involved in protests over the Israel-Hamas war. Stefan Jeremiah/AP Related article Columbia student protesters are demanding divestment. Here’s what the university has divested from in the past However, university investments are much more complicated these days. “The economy is so global now that even if a university decided that they were going to instruct their dominant management groups to divest from Israel, it would be almost impossible to disentangle,” Nicholas Dirks, former chancellor of the University of California, Berkeley, told CNN. “It’s not clear to me that it’s really possible to fully divest from companies that touch in some way a country with such close political and trade ties to the US,” Dirks added. Fully divesting from major American companies like Alphabet (Google’s parent company) and Microsoft, may come with its own set of challenges. Most Americans’ retirement accounts are invested in big tech companies, and any funds that track the broader stock market will likely hold a stake in these companies, due to their size and relative importance to the market. CNN’s Ramishah Maruf, Clare Duffy and Nicole Goodkind contributed reporting.