Trading in shares of Apple, Microsoft, Facebook, and the approximately 3,700 other companies listed on the NASDAQ exchange was suspended for much of Thursday after a technical glitch forced the market to shut down. Trading halted at 12:14 p.m. ET and stayed at a standstill until activity slowly began to pick back up at 3:00 p.m, fully resuming only at 3:30, one half-hour before market close.
NASDAQ left traders and investors in the dark for much of the day, refusing to explain the problem and generating confusion among traders and investors. TD Ameritrade spokesperson Kim Hillyer told TIME it had a “spike” in questions from customers about the outage and a “small number” of clients whose trades were impacted. “We are currently in the process of communicating with them regarding the matter,” said Hillyer. A Charles Schwab spokesperson declined to comment.
In a statement issued late Thursday afternoon, the exchange said a computer problem was preventing price quotes from being shared. Once that glitch was discovered, trading was halted on all NASDAQ-listed securities on all markets — securities listed elsewhere were still tradable on other exchanges. NASDAQ said it fixed the technical problem “in the first 30 minutes,” but maintained the trading hold to “ensure an orderly re-opening of trading.” Traders reported generally smooth sailing once the market reopened, though shares in NASDAQ itself closed down 3.4% after climbing back up from a 5.4% drop on the day.
NASDAQ said Thursday evening the technical problem has since “been identified and addressed.”
Securities and Exchange Commission Chair Mary Jo White said in a statement that Thursday’s “interruption in trading, while resolved before the end of the day, was nonetheless serious and should reinforce our collective commitment to addressing technological vulnerabilities of exchanges and other market participants.” White said she will be meeting with leaders of the top exchanges to “accelerate ongoing efforts to further strengthen our markets.”
White stopped well short of suggesting that a formal investigation of the NASDAQ glitch would follow. However, Josh Brown, a financial advisor at Fusion Analytics and frequent marketplace commentator, told TIME he wouldn’t be surprised if one came.
“It’s very possible there’s no wrongdoing here. You just have a lot of higher-ups on vacation and something went wrong,” said Brown. “But this is what the regulators are there to do, to determine whether or not we have a chronic problem. And we may not. It may turn out to be something fairly innocuous that could be fixed and never happen again. But I would be shocked if somebody didn’t at least put in an inquiry.”
Still, some say the problem could have been worse. With many market players on one last vacation before the September surge, August is a notoriously slow trading month. “It’s fortunate that something like this occurred in the dog days of August, usually the slowest period on Wall Street with many traders and investors on vacation,” David Yermack, finance professor at New York University’s Stern School of Business, told TIME.
The August slowdown is exactly what makes Thursday’s trouble so mysterious. NASDAQ’s technical woes recalled similar problems that plagued Facebook’s less-than-graceful IPO last May, but the Facebook foul-up was at least easily explicable: Such a heavily anticipated initial public offering sparked enormous investor interest, putting heavy strain on the exchange’s systems. NASDAQ has since paid $10 million to settle civil charges from the SEC over the botched IPO.
Without more information from NASDAQ, the glitch that caused Thursday’s shutdown isn’t so easily explained. Brown raised the possibility that shares of Apple, the most valuable company traded on NASDAQ, may have disrupted the market’s flow when they dipped below $500, perhaps triggering an automated lightning storm of selling. Apple finished the day at $502.96 a share after trading resumed.
“The thing that traders have been pointing to — and I can’t tell you that there’s any causation, but the two seemed to have happened at the same time — if you look at the way Apple shares traded a few minutes before the halt, they seemed to precipitously drop,” Brown told TIME. “It seems like once they broke down below $500, which is a pretty important level both technically and psychologically, maybe the system got overrun with limit orders or something. I’m just guessing, but it seems bizarre those things would happen at the same time and not be linked.”