A configuration issue is why trading at the New York Stock Exchange (NYSE) was suspended at 11:32 a.m. on Wednesday and did not resume again until shortly after 3 p.m., a NYSE statement emailed to SCMagazine.com on Wednesday said.
A trader alert explained that the NYSE began rolling out a software release on Tuesday evening to prepare for the July 11 industry test of the upcoming SIP timestamp requirement, with the initial release being deployed on a single trading unit.
Customers began connecting after 7 a.m. on Wednesday morning and experienced communication issues between customer gateways and the trading unit that had the new release. The determination was that NYSE and NYSE MKT customer gateways were not loaded with the proper configuration compatible with the new release.
“Prior to the market open, gateways were updated with the correct version of software and stocks opened at 9:30 a.m.,” the trader alert said. “However, the update to the gateways caused additional communication issues between the gateways and trading units, which began to manifest themselves mid-morning.”
As customers continued to report unusual system behavior, the decision was made to suspend trading.
“NYSE and NYSE MKT began the process of canceling all open orders, working with customers to reconcile orders and trades, restarting all customer gateways and failing over to back-up trading units located in our Mahwah, NJ datacenter so trading could be resumed in a normal state,” the trader alert said.
On Wednesday, Department of Homeland Security Secretary Jeh Johnson said that malfunctions at the NYSE, as well as at United Airlines, do not appear to be caused by a nefarious actor.