Soros invested a year ago after Gross moved to Janus from Pimco Getty ImagesSoros is pulling money from a fund run by Bill Gross.George Soros’s firm has pulled its roughly $500 million investment with Bill Gross because of poor returns, less than a year after the billionaire hedge-fund investor gave the former bond king his stamp of approval, according to a person familiar with the matter and industry data. The move is a blow to Gross, who has struggled with performance and outflows at his Janus Global Unconstrained Bond fund since he left Pacific Investment Management Co. last year. The money invested by Soros Fund Management was held in a separate, institutional account that followed a similar strategy as Gross’s mutual fund. Industry data provider eVestment LLC, which tracks institutional accounts at fund firms, confirmed that $490 million wasn’t reported by Janus in separate accounts managed by the firm between the second and third quarter. The trade publication Pension & Investments earlier reported on the $490 million outflow, but P&I didn’t identify the party that made the withdrawal. An expanded version of this report appears on WSJ.com