NYSE Euronext, the world's largest stock exchange, has pledged to improve the technology of its equity trading systems by the end of the year, as it reported a 73% rise in net profit for the three months to the end of September, its first full quarter as a merged company.

The transatlantic exchange said today it will increase the capacity of its main stock trading system by two thirds before the end of this year, taking its processing capacity to 64,000 messages a second. It is the second European exchange to have upgraded its main trading system in two days, following an announcement from the London Stock Exchange on Tuesday.