Nasdaq halt puts pressure on Greifeld Nasdaq OMX faced a barrage of criticism on Friday as the operator of the second-largest US stock exchange defended its handling of the longest technical trading outage in its 40-year history. The three-hour disruption a day earlier spooked US investors and prevented trading in household names such as Amazon, Apple, Google and Microsoft. The outage threatens to be a serious blow to the exchange's prestige. Pioneering reliable technology has been a central part of its identity since its formation in 1971. However, the glitch comes just over a year after technology failures marred the debut of Facebook, one of the US's largest and most eagerly awaited listings, and has put the spotlight on both Nasdaq and Robert Greifeld, the industry's highest-paid chief executive. Mr Greifeld described himself as "deeply disappointed with what happened yesterday" but suggested the problem lay in the highly fragmented US equity market in which 13 exchanges and more than 50 trading venues compete for business. He said: "Back when the market was a monopoly, starting it up was like starting a car. Now, in a fragmented landscape, it's like starting a jet engine. The problem, as Mr Greifeld acknowledged, was a failure at a little-known but critical part of the US equity market, known as the Securities Information Processor. This centralised hub consolidates all the data from the 13 exchanges and oversees the National Best Bid and Offer system, which rewards traders who register quotes closest to the best price. The SIP was agreed on by all leading market exchanges and authorities, but there is only one central hub - and it is operated by Nasdaq. While it took 30 minutes to resolve the IT issue, the rest of the time was devoted to preparing the market for resumption of trading. Mr Greifeld said the exchange bore no liability for the outage, but market participants have begun to question the management's handling of Nasdaq's operating systems. One person familiar with the company's leadership reckoned it was time for a change of management. The person said: "Time after time there is a problem at Nasdaq; they need new leaders. Bob has been there for 10 years and has been a great cost-cutter, but the core focus has not been on investing in the technology. He's been looking for a high event to leave on, but the May [Facebook] events from last year hampered that and this makes it worse. Mr Greifeld said the closure was partly for the benefit of retail investors who didn't have the same access to information as professional traders. Richard Repetto, analyst at Sandler O'Neill, said Nasdaq failed to see the bigger picture as it dealt with the breakdown. "They have been strong in saying that they didn't need to speak to media, but their role as the second-largest marketplace in the US is to keep retail investors informed," he said. If you let three hours go by, it's going to impact retail investors and if there are negative flows into equity funds, it's going to impact everyone. Mr Greifeld said: "We stand by our record over the long period of time. And we are definitely going through good times at Nasdaq OMX. Our stock is up 20 per cent for the year. We have more good things going on now than at any other time in my tenure.