The Guardian reports that a glitch in the Nasdaq stock market resulted in an unprecedented shutdown of trading of over 2,000 major US stocks and options for more than two hours, creating confusion around the shares of the biggest companies in America and resulting in calls for greater regulation.
Nasdaq shut down for over three hours in the middle of the day as it investigated the outage. Trading resumed at 3.25pm ET.
The company said the the failure resulted from a glitch in software that publishes the prices of stocks listed on the exchange. Some of the largest American companies, including Apple and Facebook, are listed on Nasdaq; about 20% of the S&P 500 companies call Nasdaq their home exchange. Despite the closure the exchange ended the day up 38 points or 1.1% at 3638.71.
Because other exchanges depend on Nasdaq’s pricing software for accuracy, the outage affected a host of other exchanges, ranging from NYSE Euronext to systems that serve primarily professional investors who trade in large blocks of thousands of shares at a time. By one estimate, the halt locked up roughly $5.7tn in shares.