This is Planet Money from NPR.

One day in 2011, Dr. Richard Sandor, economist, professor, people call him Doc.

Doc was in Chicago, reading his newspaper, the financial times, and drinking his coffee,

when his phone rang.

And I got a phone call and somebody said, did you hear about it?

Royal Bank of Scotland, they just fired for people, and I said, no, that's a game changer.

The somebody who called was a guy at one of the big investment banks.

The gossip was that Royal Bank of Scotland appeared to be firing for traders in attempt to head off a scandal.

Now, when a bank does that to get ahead of the regulator, you know it's massively corrupt, right?

The thing that was corrupt was this thing called libor.

It's an acronym, it stands for the London Interbank Offered Rate.

Libor is this magic number that helps banks figure out how much to charge to lend money out.

It's been called the world's most important number.

And it's set by a bunch of bankers asking each other, hey mates, oi brav.

You know, oi brav. What should the number be today?

So when Doc gets that phone call, he knew it wasn't going to just be a few people at one bank.

And obviously if there's one, there's got to be two, it's an economist that takes two to collude, and if there's two, there's four, right?

So...

What did you know in that moment?

That libor was dead, okay? Once they fire four people, they don't eat their own unless there's some compelling reason to do it.

So Doc thinks libor is doomed.

It was kind of unthinkable.

...