A human error at a New York Stock Exchange data center in Chicago, wherein backup systems were left running, caused the exchange’s computers to treat Tuesday’s opening bell as a continuation of the previous day’s trades.
The opening auction that normally sets prices did not occur.
“On January 24, 2023, at approximately 9:30 AM, the NYSE commenced continuous trading in 2,824 of 3,421 NYSE-listed securities without attempting to conduct an opening auction due to a technical issue,” the NYSE indicated on its website.
The commencement of continued trading in lieu of the expected opening auction that sets prices caused 84 listed stocks to be paused after hitting price band benchmarks that prevent security prices from spiking or plummeting too far too fast.
“I haven’t seen anything this crazy technologywise in 30 years in the industry. It was pretty chaotic,” an unnamed trader on the NYSE floor told the Financial Times.
Trades that met three parameters were declared erroneous and voided. These trades lacked opening auctions, happened after 9:30 a.m. but before the receipt of price bands, and were priced at a percentage beyond the price band rules.
“The exchange subsequently determined that approximately 4,341 trades in 251 symbols should be busted,” the NYSE explained.
For the 84 stocks that entered price band pauses before 9:30 a.m., trades that preceded the pause were declared aberrant and removed from the calculation of Tuesday’s high and low prices; 1,369 such trades were affected.
Eighty-one stocks also had short-selling restrictions wrongly applied, according to the Financial Times.
The cost of the incident has not yet been determined. The NYSE collects around $500,000 monthly to feed into a fund that pays out reimbursement to exchange members in the event of such mishaps.
Brokerages, however, remain concerned that human error could happen and cause the extreme fluctuation in stock prices.
“Unfortunately, the NYSE has not owned up to their full responsibility, and retail investors will have to go through a lengthy process to correct orders, with no guarantee of a reasonable outcome,” Charles Schwab spokeswoman Mayura Hooper told Bloomberg.