Three alternative trading networks had to be temporarily removed from Nasdaq Stock Market's trade reporting and quotation system last week when a software upgrade led to a slowdown of the stock market's SelectNet system.
The three electronic communications networks (ECN) that were affected - Island ECN, Instinet and BRUT - were temporarily prevented from receiving Nasdaq stock quotes.
Two of the ECNs requested to be removed from the market because of the slowness of the existing SelectNet system, which was being updated starting Tuesday night to accommodate Nasdaq's plans to begin offering after-hours trading support beginning next week.
ECNs are alternative trading networks that allow buyers and sellers of stocks to conduct transactions without Nasdaq market makers such as Goldman, Sachs & Co.
By shortly after 1pm on October 6, all three trading networks were reconnected.
Nasdaq temporarily removed the high-traffic ECNs from the system to reduce the volume of activity and help the system run faster, according to a press release issued by Nasdaq.