Some stocks moved dramatically shortly after the opening of trading on Wednesday. Wizzard Software, which closed Tuesday night at $3.50, shot above $14 in the first minutes of trading, according to data compiled by FactSet.
The glitch occurred at Knight Capital, one of the largest processors of stock trades. The company said in a statement that a "technology issue" had occurred in its market-making unit related to the routing of shares of about 150 stocks to the New York Stock Exchange.
Knight told its clients to send their orders away from its system and said it was reviewing the issue.
Knight's stock plunged $2.46, or 24 percent, to $7.87.