Nasdaq OMX, the transatlantic exchange that plans to challenge Europe’s largest stock markets when it launches a new system in September, was left red-faced today as “technical problems” meant it failed to open, leaving banks and brokers unable to trade Nordic shares for 40 minutes.

OMX said insufficient numbers of customers were able to log on to the exchange’s main Saxess trading platform at the scheduled start of trading today, forcing it to delay the market opening by 40 minutes for Swedish, Danish and Finnish stocks and an hour for Norwegian shares.