Outage had no effect on trading of stocks

Associated Press

NEW YORK

You can read all about it on social media and newspapers, but you won’t find a trace of it where it really matters: Your next 401(k) statement.

In a dramatic breakdown that once would have sent the market plunging, the world’s most iconic stock exchange, the NYSE, was forced to stop trading for nearly four hours Wednesday. Regulators put out statements. Twitter lit up with conspiracy theories. The president of the United States was briefed.

As for stocks, though, there was barely a ripple.

One reason is that trading in stocks didn’t stop at all. It just shifted from the New York Stock Exchange to other exchanges and trading venues.

“It’s like your neighborhood grocery store having a power failure,” said Keith Ross, CEO of PDQ Enterprises, which runs a NYSE rival, the PDQ ATS. “You can go to all sorts of other stores that aren’t far away.”

The NYSE said in a statement Thursday that the upgrade caused communication problems between its trading software and other systems, causing customers’ orders to not go through.

The problem became severe enough by late morning Wednesday that the exchange decided to suspend trading at 11:32 a.m. so the problem could be addressed. Orders were canceled, trading software was restarted and backup units were brought online, the exchange said.

For many ordinary Americans, there was another reason not to worry: Those who own stocks only through mutual funds are not directly affected by intraday outages.

Mutual funds, unlike individual stocks and exchange-traded funds, do not trade during the day. Their prices, which are calculated using the closing prices of stocks in the funds, are set just once every day, at the end of trading.

The NYSE reopened trading at 3:10 p.m. Wednesday, plenty of time before the 4 p.m. closing.

For much of the 223-year history of the NYSE, a long trading halt could have walloped the market. Investors in big-name stocks used to be able to trade only through the NYSE. They would hand off their orders to a broker, who would turn to a “specialist” on the floor of the stately NYSE building at 11 Wall Street charged with matching buyers and sellers.

In the 1970s, Nasdaq, an electronic exchange, began competing against the NYSE. Later came more exchanges, such as ones run by BATS Global Markets, and “dark pools,” or trading platforms that allow customers to buy and sell in large quantities without alerting the broader market.

Now stocks can be traded at some 60 exchanges and trading venues. Where once nearly all stock trades were done on the NYSE, now it accounts for less than 25 percent, according to BATS.