This is a developing story, and will be updated.

Trading resumed on the New York Stock Exchange Wednesday afternoon after an internal technical hiccup sparked a halt that lasted more than three hours.

A bulletin to traders said the relatively small NYSE MKT was set to open at 3:05 p.m. ET, while the larger NYSE was due to open at 3:10 p.m. ET. The exact opening times couldn’t immediately be confirmed.

NYSE spokesperson Marissa Arnold declined to offer specifics on the root of the issue. However, a NYSE status bulletin indicated trading across NYSE and NYSE MKT was halted on all symbols at 11:32 a.m. ET. A notice later in the day indicated all open orders had been cancelled.

NYSE’s all-electronic ARCA equities market was unaffected and continued normal operations, according to a NYSE status update. NYSE’s AMEX and ARCA options markets were also operating normally.

On Twitter the Big Board headed off any concerns that the trading halt was caused by a malicious cyberattack: “The issue we are experiencing is an internal technical issue and is not the result of a cyber breach. We chose to suspend trading on NYSE to avoid problems arising from our technical issue.”

Meanwhile, other major exchanges including Nasdaq (NDAQ), and BATS, declared so-called self-helps against NYSE, indicating they are routing trades away from the exchange. It wasn’t immediately clear when those would be lifted.

The main NYSE market handled about 13.4% of all U.S. daily volume in June on average, according to data from BATS, compared to 15.8% for Nasdaq. Thus far on Wednesday, NYSE had handled 4.2% of U.S. volume, far short of its average.

A spokesperson for the Securities and Exchange Commission, Wall Street’s top cop, didn’t immediately respond to a Yahoo Finance request for comment on the matter. The White House said it was monitoring the situation, but noted the issue was not sparked by a malicious player.

Shares of the IntercontinentalExchange (ICE), NYSE’s parent, were down 2.2% in late afternoon action, compared to a 1.6% drop for the broad S&P 500.

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Nasdaq suffered from the so-called Flash Freeze just about two years ago in which a “combined series of technology events” halted trading on the electronic exchange for about three hours. Initially, it was thought that high-frequency trading could have played a role in the freeze, but Nasdaq eventually said that was not part of the cause.

‘Chugging along’

U.S. stocks were down sharply on Wednesday, but traders attributed the move to worries about China and Greece.

Michael Block, chief strategist at Rhino Trading Partners in New York, noted volume was already light before the NYSE issue, and has since narrowed. However, he said “stocks are trading so we’re chugging along.”

As of 2:49 p.m. ET, the S&P 500 was off 31.1 points, or 1.5%, the Dow Jones Industrial Average was down 242 points, or 1.4%, and the Nasdaq Composite shed 85.2 points, or 1.7%.

China’s Shanghai Composite, which already fell into bear-market territory, plummeted 5.9% overnight in volatile action. The move came despite attempts by the country’s government to shore up the equity market there.

“Let’s not call it a correction in China, let’s call it what it really is, a crash. Just because it didn’t happen in just one day like other so called crashes doesn’t make it any less so,” Peter Boockvar, chief market analyst at The Lindsey Group, wrote in a note to clients.

“What is most significant though is that it came in the face of almost every attempt possible by Chinese authorities to prevent it from happening.”