(Bloomberg) The world’s biggest ESG fund category is also by far its most opaque, and that’s starting to bug investors.Most Read from BloombergTrump Signals Support for Johnson’s Bid to Become House SpeakerControversial Chip in Huawei Phone Produced on ASML MachineChina Developer Country Garden Deemed in Default on Dollar Bond for First TimeS&P 500 Falls 1% as Bond Yields Rise; Oil Gains: Markets WrapNobody Wants Mutual Funds NowAsset managers are sitting on roughly $6 trillion of funds regis