On May 6, 2010, the Flash Crash occurred.

Finally a non-technical short story that explains how it could have happened and how it might happen again.

The latest article to mention the Flash Crash is http://www.usatoday.com/story/money/markets/2013/02/13/dow-nears-new-peak-amid-eerie-calm/1912509/

Click on Flash Crash Epitaph  to read this short story.  Enjoy!