One market structure alternative that is gaining some traction in US equities is PDQ: http://www.pdqenterprises.com/faq.html http://www.pdqenterprises.com/faq.h

One market structure alternative that is gaining some traction in US equities is PDQ: http://www.pdqenterprises.com/faq.html http://www.pdqenterprises.com/faq.html Basically, liquidity providers upload their market making algo to the matching engine. Every time an order comes in, there is a 20ms 'mini auction' in which market making algos compete on intelligence and not on speed.