Trading Algo Can Cause Market Crash

2010 Flash Crash
http://en.wikipedia.org/wiki/2010_Flash_Crash

Algorithm Trading Responsible For Another Glitch
http://community.nasdaq.com/News/2012-08/algorithm-trading-responsible-for-another-glitch.aspx?storyid=161597

Did a Rogue Algo Cause BATS IPO Crash?
http://www.advancedtrading.com/algorithms/232800284

Markets crash due to faulty algorithm? Traders must be forced to bear the losses
http://articles.economictimes.indiatimes.com/2012-05-06/news/31588222_1_algorithmic-listing-exchange-turnover