NYSE Euronext was forced to delay trading in the most liquid Portuguese stocks by more than two hours this morning, after the exchange suffered its second operational glitch since installing a new high-tech trading platform in February.

The New York-based exchange delayed the start of trading for stocks in the main Portuguese index, PSI 20, as well as for some Dutch and French equities, exchange-traded funds and bonds, according to a spokeswoman. Trading of stocks in France's Cac 40 index and Dutch index AEX was not affected, she said.