Stock market regulators in Hong Kong and elsewhere in Asia are getting increasingly concerned at the rapid growth of what are known as 'dark pools'.
Happily, their misgivings are largely misplaced - at least for the time being - but their vigilance is comforting.
If you have never heard of dark pools, don't be too surprised. Their very name sounds exotic and mysterious, like a theoretical deduction from one of the strange outer reaches of cosmological physics or perhaps an emerging phenomenon of large scale cloud computing.
In fact, dark pools are off-exchange wells of stock market liquidity which institutional investors can tap into to buy or sell large blocks of shares without publicly declaring their intentions in advance to the rest of the market.
Dark pools are not a new idea but they are growing fast and they are opaque, both factors which make regulatory alarm understandable.
In the United States similar off-exchange order matching systems have captured as much as 10 per cent of stock market trading volume.
They are growing quickly in Asia too. David Klinger, managing director of dark pool operator Liquidnet, which started trading in Hong Kong at the end of last year, says his institutional membership has leaped from an initial 30 to 90 at the end of June.
