Bringing volume to dark pools has never been the preferred route for large size investors, but always has been more seen as "the best option out of a whole bunch of bad ones".
Dark pools are therefor a gigantic 'improvement opportunity' and aided by regulatory changes regarding dark pools in 2017, exchanges are finally stepping up to the plate.
Today BATS Chi-X announced that they will introduce a new orderbook next month with a size priority in an auction like model throughout the day. The auctions will have intervals between 100 miliseconds and 5 minutes depending on stock liquidity. The auctions will run alongside the regular orderbook which does not close during the auction.
The new orderbook will go live on 19 October 2015. Read the full press release here