The share prices of a number of Nasdaq-listed companies such as Amazon, Apple, Google, and Microsoft appeared to sit at exactly $123.47 on Monday evening, due to "improper use" of Nasdaq test data by third-parties, the exchange said on Monday.
Amazon saw its share price tumble from an opening price of $972.79 a share, while game developer Zynga experienced a 33-fold hike from an opening price of $3.65. The share prices of companies such as Facebook, however, were unaffected.
Nasdaq clarified that there was no technical glitch in its systems, attributing the inaccurate prices to the "improper" use of data that was released by the Unlisted Trading Privileges (UTP) as part of normal evening test procedures.
Due to the July 4 break, the stock market closed three hours early, after which the testing procedures began.
The data generated from those procedures were then "improperly" propagated by financial websites such as Bloomberg, Google Finance, Reuters, and Yahoo Finance, thereby portraying inaccurate share prices.
"The systems send out test data as normal course of business; unfortunately some third party vendors misinterpreted the test data," a spokesperson from Nasdaq told ZDNet.
The Nasdaq website itself presented accurate share prices.
"Any data messages received post 5:16 PM should be deemed as test data and purged from direct data recipient's databases," the second-biggest US exchange said in a statement.
"UTP is asking all third parties to revert to Nasdaq Official Closing Prices effective at 5:16 PM."
Nasdaq has dealt with data feed issues previously; in 2013 trading was suspended for three hours as a result.
Nasdaq also stopped trading for more than three hours in 2012, delaying the start of Facebook's public flotation. Another outage later that year saw public trading come to a halt for three hours due to a connectivity issue between an unnamed exchange participant and the Securities Information Processor.
The New York Stock Exchange (NYSE) went down for four hours in midday trading mid-2015, at the height of China's stock market meltdown and the Greek debt crisis.
The NYSE at the time said it had to halt trading due to residual "communication issues" between customer gateways and trading units following a software update.
The Australian Securities Exchange (ASX) experienced a series of technical issues and errors in September last year due to hardware failure. The ASX had experienced three outages over the last decade prior to the incident.
Updated 7.30 pm AEST 4 July 2017: Nasdaq clarified that there was no glitch in its systems and updates have been made to the title and article to reflect that.