U.S. stock plunge raises alarm on algo trading

A spine-chilling slide of nearly 1,000 points in the Dow Jones Industrial Average, its biggest intraday points drop ever, led to heightened calls for a crackdown on computer-driven high-frequency trading. The slide, which in one 10-minute stretch knocked the index down nearly 700 points, may have been triggered by a trading error. Major stock indexes eventually recovered from their 9 percent drops to close down a little more than 3 percent. http://in.reuters.com/article/businessNews/idINIndia-48296920100506

Stock sell-off leads to faulty trade probe 
Securities and futures regulators said late Thursday they were working with exchanges to examine "unusual" trading activity during the day's massive sell-off, which saw bellwethers such as Procter & Gamble Co. plunge nearly 40%, and a senator called for tighter trading controls. http://www.marketwatch.com/story/stocks-sell-off-leads-to-faulty-trade-probe-2010-05-06
Program trading lambasted after Dow drops 1,000 points and then snaps back, Nasdaq to cancel trades http://www.reuters.com/article/idUSTRE6456QB20100507