New York Stock Exchange system issue caused trading pauses at open

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The New York Stock Exchange said Tuesday that a system issue causes continuous trading of a subset of its listed securities at 9:30 AM ET, without an opening auction print.

As a result, a number of core trading session trades occurred before the receipt of Limit Up Limit Down bands. The NYSE said those trades are eligible under an NYSE rule to be reviewed as "clearly erroneous."

Some high-profile stocks affected by the snafu included: Altria Group (NYSE:MO) -0.1%, 3M (NYSE:MMM) -6.2%, Morgan Stanley (NYSE:MS) -1.7%, McDonald's (NYSE:MCD) +0.1%, and Verizon Communications (NYSE:VZ) +2.0%.

Any trades in NYSE-listed symbols that did not conduct an opening auction and both occurred before 9:30:00 AM but before the receipt of LULD bands 9 (generally less than a second later) and executed at a price exceeding percentage parameters from the reference price (as defined in NYSE rules), will be declared "null and void," the NYSE said.

In addition, for those securities that didn't conduct an opening auction and entered LULD pause before 9:30:45, the exchange is evaluating marking the trades as aberrant on the consolidated tape. That would eliminate those executions from the calculation of the day's high or low price.

The consolidated tape adjustments will be processed after Tuesday's close, the NYSE's statement said.

All NYSE exchange systems are currently operational, the subsidiary of Intercontinental Exchange (NYSE:ICE) said. ICE shares fell 2.2% in late Tuesday trading.

Earlier, unusually high number of stocks halted at NYSE open.