Three years after China opened its 2.5 trillion yuan ($355 billion) hedge fund market to global asset managers, the industry is discovering just how hard it is to win over the country’s investors. BlackRock Inc., Man Group Plc and 20 other foreign firms licensed to run Chinese hedge funds -- or private securities funds, as they’re known locally -- amassed around 5.8 billion yuan of assets as a group till August, according to data compiled by Shenzhen PaiPaiWang Investment & Management Co.