Following the early close on Monday, 3 July for the Independence Day holiday, NASDAQ produced test data that showed huge changes in the prices of many prominent stocks, including Amazon, Apple, Google and Microsoft. Though the data was simply part of a standard test, some vendors, including Bloomberg, ICE and Google Finance, published the quotes. This caused confusion among market participants, however, no trades occured at the prices published thanks to the early closure of cash equities.
Under SEC rules, exchanges are allowed to trade securities for which they do not have the listing under what is called "Unlisted Trading Privileges" (UTP). NASDAQ's fictitious data was used to test its UTP quote feed. Reportedly, the exchange had warned vendors a week in advance that such a test would be occuring and so they should have known to ignore the data coming from NASDAQ.