Trading on alternative equities exchange Turquoise was disrupted on Monday by “network and firewall-related issues" leaving some brokers unable to trade for 10 minutes.
The problems forced traders on the new exchange, which had its soft launch last month, to move to a back-up system.
While most of its 35 member firms were switched over automatically, a "handful" of users had to move over manually, leaving them out of action for up to 10 minutes.
The exchange is investigating why some firms were not switched over automatically, but the impact of such an outage, in terms of lost trades, would have been "negligible", according to sources close to the situation.
Backed by nine large investment banks, Turquoise is one of a number of technologically sophisticated trading facilities that are set to launch in Europe over the next three months following the introduction of the European directive, MiFID.
Turquoise went live on 15 August and has since been adding new markets to the offering, recording its first day at full capacity, almost 1,300 stocks in 13 European countries, on Friday (29 August).
Turquoise is still building to its full launch later this month, but had its biggest trading day on Tuesday, executing 40,000 trades, and has already taken more than 10% of the daily volume market share in two leading European stocks.