A few things.
A Gordon Gekko type boss wouldn't have any interest showing off his Gordon Gekko type style.
The show has no real interest in spotlighting any financial type companies, because the boss would still be doing "white collar" type jobs even if he is doing lower level work. They want companies that require a boss to do labor, get dirty, ect. Being a bank teller a local bank branch wouldn't fit the bill.
The show is flawed as it is. I bet the employees always know beforehand that something is up. Even before the show was a success. I remember when I worked at a big steakhouse. We would always know when a suprise visit from the big bosses was coming. The reason we always knew was because the 1 big boss up there that was incharge of our area, would call the regional manager, and warn him to make sure everything is good, so that he doesn't look bad. The regional manger would then call the general manager and warn him, so he doesn't look bad. The general manager would then warn the employees, so he doesn't look bad.
Point being i'm sure a chain of command warning system happens in almost all these cases, because what it comes down to is people want to protect their own arse. The boss will tell the people in the board room not to tell anyone, but the guys in the board rooms will be the ones who get introuble if things aren't going the way the big boss is told they're.