"We can observe this, but we don't have concrete statistics, so we're unclear on the scope," said Zeng Gang, director of the banking department at the Chinese Academy of Social Sciences, a think tank that advises the central government.  Shadow banking is therefore harder to regulate, he said.  Indeed, the State Council called on the central bank last December to develop new statistics to measure shadow banking.  In shadow banking's new incarnation, brokerages and fund management companies can pool retail investor funds or invest funds already gathered by a bank, acting as an intermediary rather than the actual investor.  "China's credit landscape is just simply evolving too quickly, so TSF doesn't provide as comprehensive a picture as it used to do," said Donna Kwok, an economist at UBS.  Shadow banking, defined as non-bank credit and off-balance sheet bank lending, is an important part of banking systems around the world. In China, it has helped smaller, private companies access credit and offered investors better returns than bank deposits.  The central bank has said the benefits of the sector are undeniable.  But it can also fund risky or unproductive investments, building up risks in the banking system. This is what authorities are trying to tackle.  As the China Banking Regulatory Commission (CBRC) clamped down on trust companies and off-balance sheet lending, the sector adapted to capitalize on CSRC rules from 2008 that allowed brokerages to launch asset management subsidiaries.  Read MoreChina's shadow banks need 'close monitoring': IMF  Investment consultancy Z-Ben Advisers said these units had more than tripled assets under management from 1.89 trillion yuan in 2012 to 6.82 trillion at the end of June.  Fund management firms followed suit, growing from 100 billion yuan in 2012, the first year they were allowed, to 2 trillion at the end of June.
China's shadow banking sector is growing rapidly despite tightened rules, taking advantage of a regulatory anomaly to prosper.