If you blew town Aug. 15 for a one-week remote-island getaway, you could have concluded upon returning that you hadn't missed a thing on Wall Street. The Dow Jones industrial average was at 7942 when you departed; 7894 when you reappeared, a pimple of a drop. But you would have been wrong--and missed the perverse pleasure of watching hordes of young traders sweating through their custom-made threads while the market extended and retracted like a bungee jumper flung off the George Washington Bridge.
The Dow rose or fell at least 100 points all five days that week, part of a numbing...