Media playback is unsupported on your device

Stock markets under computer control

8 July 2013 Last updated at 10:33 BST

Over the last decade, computer algorithms have changed the way that that stock markets function.

BBC News business editor Robert Peston has been investigating their impact on trading floors.

Xavier Rolet, from the London Stock Exchange, explained on the Today programme why there had been such a dramatic change in the way the stock market functioned.

"I think they've been the inescapable and logical consequence of regulatory changes," he said.

"Some of these consequences have been unintended but ultimately the decision was not made by the exchanges and should not be laid at their door."

First broadcast on the Today programme on Monday 8 July 2013.