A trading halt on the Nasdaq Stock Market NDAQ +0.82% neared an hour after an unexplained technical issue, paralyzing the market for thousands of securities and raising new questions about the robustness of U.S. trading systems following a series of high-profile glitches.
The second-largest U.S. stock exchange expected to resume trading shortly, a person familiar with the matter said just after 1 p.m. ET. The exchange said in a notice to traders that it wouldn't cancel open orders, but that customers could do so. The exchange would resume trading at a time "to be determined," the notice said.
The outage saw a large chunk of the U.S. stock market effectively come to a standstill at midday, freezing prices in stocks, exchange-traded funds and options listed on Nasdaq and prompting other trading venues to stop trading those securities. Dark pools and other electronic trading platforms were also forced to suspend trading in Nasdaq-listed stocks, since there were no publicly quoted prices on those securities, traders said.
Traders said there was confusion about what stocks were affected, and that phones were lighting up across trading desks as investors tried to figure out what as happening.
"We're pulling out our orders to wait until the system works itself out," Rick Fier, director of equity trading at Conifer Securities. "The best thing clients can do is take a break."
