On Monday the system that feeds real-time data feeds to data providers and is used to calculate index values, experienced a processing issue that resulted in some delayed quotes. An example impact of this glitch is that some of Vanguard’s funds appeared to lose as much as half their value on Monday.
Some traders alerted CNBC to the issue, saying it was affecting the quote for the Dow Jones Industrial Average, which traded in a flat range in about the last 50 minutes of trading. Index values may have been impacted by the processing delay, but all trades were completed appropriately, the sources said.