Billionaire investor George Soros says he regrets his firm's investment in Palantir Technologies. : It’s common for fund managers to talk up their investments. Billionaire investor George Soros is taking the opposite tack. His family office, Soros Fund Management, issued a statement criticizing one of its holdings, Palantir Technologies PLTR, +12.05%, after a Securities and Exchange Commission filing revealed it had a roughly 1% stake in the data analytics company.