There was one overlooked fact in a European Central Bank working paper on high-frequency trading published this month. On page 25 of 57, the report’s authors gave an estimate of the combined global revenue pool of HFT firms. It was $5 billion a year.

If proof was ever needed, the figure demonstrated that high-speed trading has become a multibillion-dollar business, and one in which stock exchanges, brokers and technology providers have a huge stake.