Trading on the floor of the exchange stopped at 3:23 P.M., when the Dow achieved its maximum allowable fall of five hundred points. That figure merely reflected the value of thirty stock issues, and the fall in others well exceeded the benchmark loss of the biggest of the blue chips. The ticker look another thirty minutes to catch up, offering the illusion of Further activity while the people on the floor looked at one another, mostly in silence, standing on a wood floor so covered with paper slips as to give the appearance of snow. It was a Friday, they all told themselves. Tomorrow was Saturday. Everyone would be at home. Everyone would have a chance to take a few deep breaths and think. That's all that had to happen, really, just a little thought. None of it made sense. A whole lot of people had been badly hurt, but the market would bounce back, and over time those with the wit and the courage to stand fast would get it all back. If, they told themselves, if everyone used the time intelligently, and if nothing else crazy happened.

They were almost right.

At the Depository Trust Company, people sat about with ties loose in their collars, and made frequent trips to the restrooms because of all the coffee and soda they'd drunk on this most frantic of afternoons, but there was some blessing to be had. The market had closed early, and so they could start their work early. With the inputs from the major trading centers concluded, the computers switched from one mode of operation to another. The taped recordings of the day's transactions were run through the machines for collation and transmission. It was close to six in the evening when a bell sounded on one of the workstations.

"Rick, I've got a problem here!"

Rick Bernard, the senior system controller, came over and looked at the screen to see the reason for the alert bell.

The last trade they could identify, at exactly noon of that day, was for Atlas Milacron, a machine-tool company flying high with orders from the auto companies, six thousand shares at 48 1/4. Since Atlas was listed on the New York Stock Exchange, its stock was identified by a three-letter acronym, AMN in this case. NASDAQ issues used four-letter groups.

The next notation, immediately after AMN 6000 48 1/4, was AAA 4000 67 3/8, and the one under that AAA 9000 51 1/4. In fact, by scrolling down, all entries made after 12:00:01 showed the same three-letter, meaningless identifier.

"Switch over to Beta," Bernard said. The storage tape on the first backup computer system was opened. "Scroll down."

"Shit!"