Current and former employees alleged that the foundation's top fundraiser, Mari Ellen Loijens, regularly bullied and spoke down to co-workers, made sexually and racially insensitive comments and sometimes threatened to use physical violence.

While CEO Emmett Carson expressed regret "that former staff felt they could not report inappropriate behavior and urge any other staff to come forward," 65 current workers called him out in a letter they sent to the board.

"They knew about her behavior," read the statement. "And, through their inaction, senior leadership and HR has created and reinforced a toxic culture of fear, blame and intimidation."

The board had placed Carson on leave days after receiving the letter and Daiva Natochy, the HR director, left the foundation. Last month, Carson was fired following the release of a report that investigated the bullying and harassment allocations, the San Francisco Chronicle reports.

As of February, the foundation managed $13.5 billion in assets, ranking it third behind the Bill and Melinda Gates Foundation and the Open Society Foundations.