You should be careful what you wish for because you might just get it. For years, investors, brokers and traders have longed for faster, deeper, cheaper and more competitive equity markets. Now they have got what they wanted, and suddenly a lot of people would like to wind back the clock.

The relentless progress in equity markets over the past few decades is a parable for the capital markets and investment banking industry. The combination of deregulation and technology has triggered an explosion in trading volumes, a proliferation of competing trading venues and a collapse in the cost of trading.