The growth of computerised trading has brought obvious benefits to investors.

And he's keeping a close eye on computerised trading.

Trading firms may also need to "stress test" their computerised trading models or algorithms before they go live.

Another theory is that a huge computerised trading program was triggered by a big currency-related play amid the deepening Greece-related crisis.

French Economy Minister Christine Lagarde said a form of computerised trading known as high-frequency trading (HFT) may need banning in some cases.

Fast computerised trading also played a role in the "flash crash" when Wall Street blue chips briefly went into freefall in 2010.