Investors who wanted to buy and sell shares of companies listed on the New York Stock Exchange, such as IBM or Target, were still able to do so with ease on Wednesday.
In years past, a shutdown of the NYSE might have stopped Wall Street dead in its tracks, with a broad range of companies' shares sitting frozen until all technical problems were unwound.
But as the lengthy stoppage on Wednesday showed, the modern world of stock trading is much quicker, more complex and reliant on sophisticated computers - and in many cases able to adapt to issues that could have proved disastrous to the financial markets and the investors' holdings.
Now, an immense amount of trading takes place on so-called off-exchange venues, including the private stock trading platforms known as "dark pools" that let investors buy and sell shares without tipping their hands to the broader markets.
Those alternative markets have multiplied as big investment banks like Credit Suisse and Goldman Sachs have waded into the business. Dark pools now make up roughly 40 per cent of all stock trading volume.
That means that customers can still find plenty of other alternative venues to do business.
Such complexity has drawn criticism from analysts and investors who have complained that fragmentation of the stock market world has made the business much more fragile and has provided opportunities for so-called high-frequency trading firms that can execute trades in milliseconds. Yet, that splintering has also provided investors with something of a safety net against many problems.
The diversification of trading has been blamed for an array of problems that have bedeviled the markets over the years. But analysts say that spider web of systems has also made issues like the NYSE's less catastrophic than they once might have been.
"It's much more complicated, but much more robust," said Larry Tabb, the founder of the Tabb Group, a financial market research firm.
Long gone are the days when the only exchanges around were the Big Board and the Nasdaq, with floor traders handling huge percentages of stock trading by hand. A monthslong shutdown of the New York exchange in 1914, at the onset of World War I, virtually eliminated stock trading in the country until the exchange reopened.
Now there are 11 exchanges, including three owned by the NYSE, three by the Nasdaq and four by BATS Global Markets, one of the biggest electronic markets around. And the average E-Trade or Charles Schwab customer, for instance, should not have even noticed that there was any problem, because many of these brokerage firms use those other exchanges.
"This is negative for those who complain that market fragmentation is hurting liquidity and small investors," Jaret Seiberg, an analyst at Guggenheim Securities, wrote in a research note on Wednesday. "Yet fragmentation also means there is still robust trading even when a major exchange experiences a technical glitch. To us, this makes it harder to fight against."
The N.Y.S.E. itself is now a subsidiary of the Intercontinental Exchange, which began in Atlanta as a way to buy and sell electricity. It has commanded more than 24 percent of public stock trading volume over the last month, according to data from its competitor BATS. BATS said that it handled about 20 percent, and Nasdaq oversaw under 19 percent. It is a far cry from 1997, when the N.Y.S.E. and Nasdaq handled 80 percent of stock trading volume, according to Bloomberg data.
Gone, too, are the days when N.Y.S.E.-listed stocks could be traded only on the Big Board, and Nasdaq-listed shares on that exchange. Now each of the 11 stock exchanges can handle trades in any issuer. Thus, if one market goes down, others are able to pick up the slack.
Such was the case on Wednesday, making the halt of the N.Y.S.E. less severe than it could have been otherwise. (The stoppage did affect indexes that rely on the prices originating from primary listing markets, though with the Big Board having resumed trading by late afternoon, that was less of an issue.) Still, more serious problems can grind trading to a halt altogether. Seared into many traders' minds is the 2010 flash crash, when a cascade of technical errors prompted huge swoons in the market before prices rebounded within a half-hour.
Then two years ago, system problems shut down the Nasdaq for three hours, stopping trading in huge names ranging from Google to Apple in what became known as the "flash freeze."
Investors, however, need not rely on traditional exchanges to trade their shares at all. Before, orders would flow to the brokers on the N.Y.S.E. floor, who would then turn to specialists who hand-matched would-be sellers with interested buyers. Now, many Wall Street firms execute trades within their own systems.
"There are many other alternative places to trade," Mr. Tabb said. The only ones who suffer from that, he added, are the exchanges themselves.
© 2015 The New York Times News Service
