Regulators can add a faulty software update at NYSE Euronext’s electronic Arca stock market to the list of mishaps that have weighed on investor confidence.
A system upgrade at Arca triggered what appeared to be a 9.6 percent plunge yesterday in an exchange-traded fund that tracks the Standard & Poor’s 500 Index, a drop that would have erased $7.9 billion from one of the most popular securities in the U.S. Data published by the electronic venue at 4:15 p.m. New York time showed the SPDR S&P 500 ETF Trust at $106.46, compared with its opening level of $117.74.
