"August 1st will be another day that will destroy investor confidence just like the May 6th  flash crash."
That rather ominous sounding pronouncement comes from Joseph Saluzzi, co-head of equity trading at Themis Trading LLC in Chatham, N.J., in a Bloomberg News report about what happened early this morning on Wall Street.
"U.S. stock traders Wednesday grappled with a wave of orders that roiled the market and prompted exchanges to halt trading in some securities, raising concerns that another technology problem may dent investor confidence."
The Associated Press writes that "the New York Stock Exchange said it was reviewing trades in 140 stocks. Trading volume was unusually high in the first half-hour of trading, and some investors suspected technical glitches."
According to Bloomberg:
"The New York Stock Exchange and Knight Capital Group Inc. said they were investigating. Goodyear Tire & Rubber Co. rose more than 10 percent in the minutes after the 9:30 a.m. open in New York. Manitowoc Co. gained 14 percent, Pandora Media Inc. climbed almost 11 percent and Level 3 Communications Inc. plunged 15 percent before the swings narrowed minutes later, according to data compiled by Bloomberg."
The Journal adds that:
"Traders described unusual price swings in some stocks early in the trading session amid a large number of buy and sell orders blasted across electronic trading platforms. ...
"Clients of Knight's trading services, including retail brokerage firms and institutions, were instructed to send their stock orders elsewhere due to technical problems, according to people involved in the situation. The system error and reports of irregular trading stoked suspicions that trades had been accidentally duplicated via computer algorithms, rather than the problem being contained to one server, as has happened in the past, traders said."
As of this moment (12:45 p.m. ET), the overall market seems to be holding steady. The Dow Jones industrial average is up about 33 points, or 0.25 percent.
Update at 3:55 p.m. ET. NYSE Cancels Trades For Six Stocks:
Bloomberg and The Wall Street Journal are reporting that the New York Stock Exchange is continuing its investigation, but has decided to cancel trades in six stocks.
"The six securities affected are Wizard Software Corp. (WZE), China Cord Blood Corp. (CO), Reaves Utility Income Fund (UTG), E-House (China) Holdings Ltd. (EJ), American Reprographics Co. (ARC) and Qicksilver Resources Inc. (KWK).
"NYSE has "determined to cancel all trades in the following six symbols," NYSE said in a trader notice. "Trades executed 30% or more above or below the opening price today between 09:30:00 a.m. and 10:15:00 a.m. ET will be busted."