The New York Stock Exchange started having problems with a new software upgrade more than two hours before Wednesday’s opening bell but tried to patch it up before trading started — unsuccessfully as it turned out.
The exchange, owned by Atlanta-based Intercontinental Exchange, issued a statement on Thursday elaborating on the software snarl that caused the world’s largest stock exchange to be shut down for more than 3 1/2 hours a day earlier.
Trading on the NYSE was back to normal on Thursday, but some participants said it’s likely the U.S. Securities and Exchange Commission will investigate what caused the unusual shutdown and whether the stock exchange had adequate systems to recover from an emergency.
Customers began having “communication issues” shortly after 7 a.m. Wednesday after the NYSE installed new software, the exchange said in Thursday’s statement. To fix the problem, the exchange said, it also updated customers’ connections with new software before the market opened at 9:30 a.m.
“However, the update … caused additional communication issues” that showed up about mid-morning, the NYSE said, so it issued a warning to customers and shut down trading at 11:32 am.
It would take until 3:05 pm before the NYSE re-opened the market using its back-up systems in Mahwah, N.J.
The NYSE and ICE did not elaborate beyond Thursday’s statement, or answer questions. The NYSE had said early Wednesday that a cyber attack was not the cause of the market interruption.
