Investors in Cerberus Capital Management LP are pressuring the investment firm to unload their shares of Freedom Group, maker of the Bushmaster rifle, the weapon used to massacre 20 children and 6 adults in a Newtown elementary school last December.

The University of California stated that they do not want to be owners of companies that make weapons. The institution has an indirect investment of $1 million in Bushmaster via their much larger investment in a Cerberus private equity fund.

“We do not want to have investments in companies that sell, manufacturer or distribute firearms,” spokeswoman Dianne Klein said on Tuesday.

Other huge investors have stakes in Cerberus funds, including some of the country’s largest pension funds. The California State Teachers’ Retirement System announced after the Sandy Hook murders that it was going to review its holdings with Cerberus.

Not long after the shootings Cerberus said they were looking for a buyer for the Freedom Group. They hired an investment bank, Lazard Ltd. to help sell the company. Banking sources have said that major Wall Street companies are refusing to finance a bid for the Freedom Group.

Stephen Feinberg, founder and senior partner at Cerberus may bid for Bushmaster himself, together with a consortium of other senior partners from Cerberus. The move is considered a “stalking horse” offer which is a way to induce competition for the purchase of the Freedom Group, which is a collection of merged gun companies, including Bushmaster, which Cerberus bought in 2006. Freedom Group’s sales rose by 20 percent to $931.9 million in 2012.