Two really smart Wall Street guys, Bill Ackman of the Pershing Square hedge fund and Steve Roth of Vornado Realty Trust, bought tons of J.C. Penney (Fortune 500) stock and got its board to hire Ron Johnson, the architect of Apple's wildly successful retail operation, to run this archetypal Main Street company. Johnson famously decided to take the whole chain upscale all at once without doing any testing. He discovered what anyone who has spent more than three seconds in a JCP store could have told him: that selling underwear to bargain hunters isn't the same as selling trendy, high-margin iWhatevers to buyers happy to pay full retail. , Johnson got fired this year; Ackman and Roth took big losses. The company is now struggling to survive the turkey trio. Repeat after me: Wall Street isn't Main Street.