What Dark Pools Are
A dark pool is an electronic venue at an exchange used by investment brokers to provide hidden liquidity, i.e. allow trading out-of the public’s eye in an anonymous and private manner.
Currently it is estimated that in the US around 10 to 15% of equity transactions are executed via dark pools.
Dark pools are provided by investment brokers, e.g. Goldman Sachs, JP Morgan, UBS, Morgan Stanley, etc.
They are also increasingly provided by traditional stock exchanges, like NYSE Euronext, NASDAQ OMX, LSE, SWX. This is mostly to counter the growth of new exchanges like Chi-X, BATS, Turquoise, whose business model relies on dark pools.
Here are some dark pool providers (what I could find so far):
