I thinks that's the name NMS?
no
I recognize that this is an old thread, but the answer provided by d138 should be corrected.
Dark Pools are subject to the provisions set forth in both Reg NMS and Reg ATS.
Agreed, dark pools are subject to both regulations. But while they may be filling at the mid and price improving, the problem is that they can report trades late which show up in the tape and can confuse some investors since the trade prices don't align with the current trade price.
Not to mention the added market segmentation of an already overly segmented market.