Trading in Nasdaq-listed stocks including Apple, Google and Microsoft slammed to a halt just after midday in New York as the second-largest US stock exchange by volume suffered a technical breakdown, sparking chaos and confusion among traders and market participants.

Nasdaq stock trading had not resumed after more than two hours as US exchanges scrambled to try and identify the source of the problem that affected the distribution of prices from an exchange that is home to some 2,700 companies worth about $6tn.

Nasdaq issued the trading halt at 12.14pm on what was otherwise a quiet trading in August marked by seasonally low volumes. A spokesman declined to comment on when trading would resume. The Nasdaq index was up 0.87 per cent to 3,631.17 when the system went down.

Nasdaq issued a statement saying it would reopen trading in stocks-listed on its exchange at a time to be determined. It said it would take bids and offers for 5 minutes to determine the supply and demand for share prices before trading would officially resume.

http://www.ft.com/cms/s/0/03bdef9e-0b4d-11e3-bffc-00144feabdc0.html